1. It is well known that the three main sources of demographic and social statistics are censuses, surveys and administrative records. These three data sources are the principal means of collecting basic demographic and social statistics as part of an integrated programme of statistical data collection and compilation. Together they provide a comprehensive source of statistical information for policy formulation, development planning, administrative purposes, research and for commercial and other uses.

2. While these three sources are complementary, many countries use a combination or all three methods for various reasons. Normally, countries select one of these sources to obtain statistics based on the needs of the respective data users; reliability and timeliness of the results; and practicality and cost-effectiveness of the method. In many countries, however, a particular method is used due to statutory requirements.

3. This paper will discuss the advantages and disadvantages of these three sources, taking into consideration such factors as cost, data quality and the needs of the data users.

A. Sources of demographic and social statistics

4. A combination of two or all three data sources mentioned above is often used to collect certain data in order to obtain the most accurate estimate of certain statistics. A country may employ more than one data source because the statistics are critically important for policy and development planning and no single source is able to provide sufficiently reliable estimates for those statistics. On the other hand, employing two or all three sources to collect the same statistics will certainly increase the cost of the data collection. It is therefore necessary that the national statistical authority should take such a decision only for the highly critical statistics. For example, data on fertility are often collected through all three sources[1], particularly in developing countries. The three sources may not give the same results, but countries with a lack of data often use all the sources in order to obtain better estimates of the fertility levels and trends in the country.

1. Population and housing censuses

5. Population censuses have been carried out in almost every country of the world during the past several decades, and some countries have conducted censuses for more than a century. The main reason censuses are carried out by so many countries is because a population census is the only data source which collects information from each individual and each set of living quarters, normally for the entire country or a well-defined territory of the country. Censuses must be carried out as nearly as possible at a well-defined point in time and at regular intervals so that comparable information is made available in a fixed sequence (United Nations, 1998).

6. Population censuses are the ideal method of providing information on the size, composition and spatial distribution of the population, including their demographic and socio-economic characteristics. Population censuses provide data either for the whole population or for a very large sample of the population, so that estimates may be produced for relatively small geographic areas and population subgroups. A census is also ideal for the segmentation of a population into various population subgroups based on some specified characteristics and for identifying target populations for policy and/or planning for both governments and private businesses. A population census is a very important source for population estimates needed to calculate vital rates based on data derived from civil registration. It is also important in providing the base population for the estimates of statistics obtained from demographic surveys.

7. To successfully cover all the population within a defined area in a relatively short period of time, a census must be carefully planned and well executed. The planning, preparation and implementation, which include a series of complex interrelated activities, may be broadly categorized as follows: (a) securing the required legislation, political support and funding; (b) mapping and listing of all households in all areas to be enumerated; (c) planning and printing of the questionnaires, instruction manuals and procedures; (d) establishing the logistics for shipments of all census materials; (e) recruiting and training all census personnel; (f) organizing the field operations; (g) launching publicity campaigns; (h) preparing for data processing; and (i) planning for tabulation, production and dissemination of the census results.

8. The above list is by no means complete, but these requirements for planning, preparation and implementation make the population and housing censuses the most extensive, complicated and expensive statistical operation for any country to undertake. To keep the census operation cost-effective, census organizations are usually under strong pressure to keep census questionnaires limited to the most basic items. Nevertheless, the topics to be covered in the census should be determined upon balanced consideration of (a) needs of data users in the country; (b) availability of information on the topics from other data sources; (c) international comparability; (d) willingness and ability of the public to give adequate information on the topics; and (e) available resources for conducting the census (United Nations, 1998).

9. Such balanced consideration will need to take into account the advantages and limitations of alternative methods of obtaining data on a given topic within the context of an integrated national programme for gathering demographic and social statistics to meet the national needs. The full range of national uses (for example, policy, administration and research) and national users (for example, national and local government agencies, those in the private sector, and academic and other researchers) should be considered in determining whether a topic should be included in the census. Each country's decision with regard to the topics to be covered should depend upon a balanced appraisal of how urgently the data are needed and whether the information could be obtained equally well or better from other sources.

10. While census data provide a unique quantitative foundation for use in national and subnational planning across a large number of sectors, censuses have a number of disadvantages. First, a successful census requires very large resources in terms of manpower, funds and materials, while government budgets are coming under closer scrutiny with constraints increasingly being imposed on public spending. Further, there have been recent cutbacks in the funding for international development assistance which, in the past, has been a major source of funding for censuses in many developing countries. In addition, censuses are carried out very infrequently, once in 10 years for most countries. They cannot provide detailed information on any given topic and often suffer from a variety of errors that are difficult to control. In this climate, increased attention is being focused on the resource requirements for carrying out censuses and on alternative methods and strategies for obtaining the needed data (Suharto et al., 1999).

2. Sample enumeration in censuses

11. The cost and limited number of questions that can be included in the questionnaire are the main disadvantages of a population and housing census, so many countries carry out a sample enumeration in conjunction with the census to collect more detailed information on a separate (longer) questionnaire, often referred to as the “long form”. Collecting additional topics from a sample of population or households during the census operation is a cost-effective way to broaden the scope of the census to meet the increasing and expanded needs for demographic and social statistics. The use of sampling makes it feasible to produce urgently needed data with acceptable precision when factors of time and cost would make it impractical to obtain such data from a complete enumeration.

12. The success of the sample enumeration will depend on the strict execution of scientifically designed selection procedures. The most important factors to be considered in the design are the size and complexities of the sample. The advice of sampling statisticians who are conversant in both the theory of sampling and practical operations of carrying out a sample survey in the field is indispensable at all stages of the sampling operations (United Nations, 1998).

13. The collection of more detailed information from a sample of population and households often helps to improve the quality of the data collected through the use of a smaller number of more highly qualified and better-trained enumerators. The smaller-scale census operations enable census organizations to have greater control to minimize non-sampling errors, which in a complete enumeration can be large and unmanageable, in particular, when detailed and complex questions are included.

14. The advantages of carrying out a sample enumeration as part of census operations, as compared to a separate household survey, are clear. First, the infrastructure and facilities that have been established for the census, often with large resources, are available. Second, publicity campaigns often create a state of awareness on the part of the general population regarding census activities. Such awareness is not comparable to that of any general household surveys conducted separately during the intercensal period. The momentum may also help improve the quality of data collected and may enable the census organization, if necessary, to use a larger sample size than in regular household surveys.

15. Among the disadvantages of conducting a sample enumeration in conjunction with the census operations is the risk that such additional tasks could have a negative effect on the overall census project, particularly if the census organization does not have sufficient qualified personnel to manage the sample enumeration. In such a case, the quality of data resulting from both the sample and the complete enumeration may suffer.

16. In addition, the fielding of a sample enumeration will also increase the census cost, since additional cost will be incurred for recruiting and training of more qualified enumerators and supervisors, for printing and processing a separate questionnaire, and for the additional organization and management. However, the additional cost will be offset by the advantage gained from obtaining much broader and more detailed data coverage as well as higher-quality census results. The census organization should, therefore, carefully weigh the additional census cost against the benefits gained from the sample enumeration.

3. Household sample surveys

17. Household surveys are the most flexible of the three data sources. In principle, almost any subject can be investigated through household surveys. With much smaller workloads than in censuses and the opportunity to train fewer personnel more intensively, household surveys can examine most subjects in much greater detail. While it is not possible to anticipate all the data needs of a country far into the future at the time a census is being planned, household surveys provide a mechanism for meeting emerging data needs on a continuing basis. As budgets for national statistical activities are always limited, the flexibility of the household survey makes it an excellent choice for meeting data users’ needs for statistics which otherwise are unavailable, insufficient or unreliable.

18. Many countries have instituted a continuing survey programme, which includes periodic surveys (such as annual or quarterly labour force surveys or annual surveys on cost of living, etc.) and ad hoc surveys to meet specific statistical data needs. Although ad hoc surveys may satisfy immediate purposes, they do not ordinarily provide a framework for a continuing database and time series. Continuing periodic surveys, on other hand, are normally carried out to investigate a highly important phenomenon that needs to be monitored frequently. All household survey programmes should be a part of the overall integrated statistical data-collection system of the country, including censuses and administrative records, so that the overall needs for statistical data can be adequately met.

19. Other advantages for countries that have a continuing household survey programme include the opportunity of developing adequate in-house technical and field staff that continue gaining experience with the repeated surveys over time. In addition, a continuing survey programme increases the cost-effectiveness of the available resources that have been accumulated and maintained over time, such as sampling frame, cartographic maps, the field operation infrastructure, data processing, and capacity in technical know-how both in the central office and in field offices (United Nations, 1984).

20. There are different types of household surveys that can be organized for collecting demographic and social statistics, including multi-subject surveys, specialized surveys, multi-phase surveys, panel surveys, etc. Each of these has its advantages and disadvantages and the selection of a specific programme depends upon the subject-matter requirements as well as resource considerations.

21. In multi-subject surveys a variety of different subjects is covered in the course of a single survey cycle or round. There are options for some of the subjects to be covered for all households and others to be alternated among different subsamples of households. The multi-subject surveys generally provide much greater economy than a series of surveys covering the same range of subjects.

22. Specialized surveys are concerned with a single subject or issue. The surveys can be ad hoc or part of a national survey but conducted with separate samples because of the subject matter or other considerations. They may be conducted periodically, irregularly or only once.

23. In multi-phase surveys, information is collected in succeeding phases, with one phase serving as the forerunner to the next. The initial phase normally uses a larger sample, which is screened based on certain characteristics of the sample units, to help determine the eligibility of sample units to be used in the subsequent phases. Multi-phase surveys are a cost-effective way to reach the target population in the latter phases to obtain detailed information on the particular subject under investigation. Fertility or demographic and health surveys usually adopt this type of survey.

24. In panel surveys successive surveys of the same sample units are carried out deliberately spaced over time—e.g., monthly, quarterly, half-yearly or annually—to obtain information to measure changes of certain characteristics over time. The disadvantage of the panel survey is the difficulty of maintaining the same respondents over a long period of time, including tracing those who move out of the sample areas and dealing with respondents who are fatigued or who have lost interest in the survey. One of the major advantages of this type of survey is that longitudinal measures of changing behaviour over time can be obtained. This survey is often called a “longitudinal” survey.

25. While household surveys are not as expensive as population censuses, they are costly to organize, particularly at the beginning when countries do not have a continuing programme of household surveys. As in the case of the census, household surveys are also subject to non-sampling errors as a result of the interviewing process. In addition, household surveys are also subject to sampling error, which increases quickly with the level of geographical detail sought. An adequate sample survey design is usually possible only with the availability of detailed population or household lists, maps and other geographical materials, the various control figures and other inputs which can only be obtained from a census. In this sense, the census is the major source for preparing a survey sample design.

4. Administrative records

26. The third important data source that is commonly used in many countries is administrative records. The statistics compiled from various administrative processes can be very valuable to the overall national statistical system. Many social statistics are produced as a by-product of these administrative processes—for example, education statistics from periodic reports by the ministry of education, health statistics from periodic reports based on hospital records, employment statistics compiled from employment extension services and so forth.

27. The reliability of the statistics depends upon the completeness of the administrative recording process and the completeness of the reporting system. It is very important to continuously monitor and improve the system of recording, reporting and compiling for producing such statistics since they constitute complementary sources of data to those obtained from censuses and surveys. It is also necessary as far as feasible to keep all concepts, definitions and classifications used in these records the same as those in the other data sources so that data can be compared.

28. In many developing countries, while administrative records for various social programmes can be a very cost-effective data source, they are not well developed, resulting in the unreliability of the data produced. While the administrative processes are continuing for the purposes of record keeping and administration, the compilation of statistics is secondary. Often, the administrators at the different levels of reporting offices do not receive clear guidelines on the statistical requirements that need to be maintained (concepts, definitions, classifications, timeliness, etc.). There may be a lack of effort by the statistical authority of the administration to ensure completeness and consistency of the data.

29. Among the disadvantages of administrative records are that they are often limited in content and their uses are restricted for legal or administrative purposes. Similarly, they do not usually have the adaptability of household surveys or censuses from the standpoint of concepts or subject detail. Sources of these kinds are often incomplete, inconsistent or limited in their coverage, and in many fields, such as health conditions, nutrition or household expenditures, appropriate administrative records are not available. Moreover, administrative records often focus on the individual and do not provide any information on the household or family, limiting the analytical usefulness of the data.

30. A civil registration system is one source that many countries have developed with varying degrees of success. The importance of developing a civil registration system cannot be overemphasized.It is necessary that national governments establish and maintain continuous, comprehensive and universal vital statistics to meet national needs in a timely manner. Civil registration is a major foundation for a legal system for establishing the rights and privileges of individuals in a country. Where it is comprehensively maintained, it is the main source of vital statistics (United Nations, forthcoming). The United Nations for many years has put considerable efforts into accelerating the improvement of civil registration and vital statistics systems in developing countries including: updating the principles and recommendations for a vital statistics system, organizing various training programmes, publishing several handbooks for countries which are making an effort to improve their systems and providing advisory services to countries which request them.

31. Countries that have established a civil registration and vital statistics system with reasonable completeness should be able to produce vital statistics reports from the system periodically, such as: number of live births by sex, date and place of births, complete with the demographic and socioeconomic characteristics of the mother and father; number of deaths by age, sex, place of deaths and cause of deaths complete with the demographic and socioeconomic characteristics of the decedents. Also, statistics on marriages and divorces can be generated from this system (United Nations, 1973, 1984, forthcoming). Another useful advantage for countries having comprehensive civil registration is the sense of awareness and appreciation that the general population tends to have regarding the importance of legal documents, vital statistics and administrative disciplines.

32. A reasonably complete civil registration system can further be developed into a population register system, which can provide demographic and social statistics of the population in a defined area. In particular, if the system is computerized and updated electronically from various registration points, the statistics may be produced almost at any time that the reporting is required. A population register system maintains central databases of every individual in the country, and the records are continuously updated when there are changes in the characteristics of the individual. Countries that have established a central population registry (CPR) develop a unique personal identification number (PIN) for each individual (Laihonen, 1999; Harald, 1999; Myrskyla, 1999). As an example, Danish birth statistics are derived either from the CPR or from birth registration reports prepared by the midwives (as birth attendants), who are always present when a child is born either at home or in a hospital. The midwives prepare a birth registration form, which includes the child’s birth date and sex and mother’s PIN. This report is submitted to the National Board of Health and then forwarded to Statistics Denmark to update the CPR. A similar procedure is implemented for death registration (Poulsen, 1999). It was reported that the CPR in Denmark is able to capture 99.4 per cent of births and 99.6 per cent of deaths recorded by the registration system.

33. Combined with other social and economic registers (e.g., social security registers, taxation registers, student registers, employee pension insurance registers, registers of buildings and dwellings, registers of enterprises and establishments, etc.), such a linkage can be a very powerful data source.

34. Once such a system is established, the need to conduct the traditional decennial census becomes less important, since the system can already produce basic census-type information. Many developed countries, particularly in Europe have been developing such a capacity for many years. Nordic countries—Denmark, Finland, Iceland, Norway and Sweden—have relied register-based statistics for their data needs since the 1960s and have used demographic information from central population registers since the 1970 censuses. Other countries in Europe, like Austria, Belgium, Luxembourg and Switzerland are in the process of transition from traditional to register-based censuses. Countries such as France, Germany and the Netherlands are developing a combination of various types of registers and sample surveys to produce census-type data (Laihonen, 1999; van Bochove, 1996; Eurostat and Statistics Finland, 1995).

35. It is important to note, however, that only the information that is recorded in the register can be compiled and produced as a register-based census. If, for example, there is no register data for people engaged in housekeeping, such data cannot be categorized separately. The flexibility of asking about emerging issues is no longer available as is the case in a traditional census (Myrskyla, 1999). Norway, one of the Nordic countries, has utilized its population register extensively and conducted its first census more than 200 years ago, based largely on an administrative register maintained by the church (Harald, 1999). The same register was then developed into a Central Population Register in 1960s with the introduction of the personal identification number.

36. It is necessary to understand, therefore, that developing a population register, even for developed countries, is not a short-term project and not without large investment. The success of the system may be achieved if it has the total political support of the government as well as the population at large, with established legislation, infrastructure and national budget. Some developing countries have attempted to establish a population register system; while many of them understand the benefits of developing such a register, the majority of these countries still do not totally comprehend the implications and requirements for such a development, like the need for a legal basis, administrative and organizational infrastructure, technical capacity, equipment, public awareness and cooperation, time and funding.

37. To date, except for a few countries with relatively small populations, no developing country has a comprehensive population register system. In addition, some developing countries that have initiated development of a population register system consider that the system, with unique personal identification number, is also valuable for maintaining public security and place the register under the agency that is also responsible for public security. Maintaining a register system that is also used for security purposes will be difficult because the system may not get the full support of the general population.

38. As administrative and other alternative data systems emerge and improve, they may sometimes be used to reduce the demands for censuses or household surveys. For example, where civil registration systems or central population registers are properly developed, it is possible to discontinue the collection of data on births and deaths through censuses and surveys. More often, however, administrative sources, censuses and household surveys should be seen as complementary, and census and survey planning should ensure the application of integrating mechanisms, such as the use, insofar as possible, of common concepts and subject detail in the different systems. Where this is done, it is important to check administrative procedures periodically to ensure that the proper application of these common concepts and classifications is being made.

B. Scope of demographic and social statistics

1. Data-collection methodologies

39. Demographic and social statistics, essential for planning and monitoring social and economic development programmes, include a large variety of subjects and characteristics, depending on the needs of each country. Composition of the population by age and sex and geographical distribution is among the most basic information describing any population or population subgroup. These data provide a context within which all other information—such as that on labour force, income, education, health, nutrition, migration, fertility and mortality—can be placed.

40. Section A described the three sources of data for obtaining demographic and social statistics. However, within each data source there are various ways demographic and social topics can be collected, and each method has advantages and disadvantages. While detailed methodologies of data collection are beyond the scope of this paper, examination of these topics in relation to their collection through population censuses will be made. Since each country has different data needs, stage of development, level of sophistication and funding situation, it is not possible to recommend a set of topics that could be collected through different methods that will meet the needs of all countries, particularly developing countries. In particular, this paper will discuss those topics which should be collected through complete census enumeration and which topics, if a country wishes to do so, can reasonably be collected through a census sample enumeration. It is not recommended that any country should attempt to collect all items mentioned in the list of census topics in the UN Census Recommendations[2]. Rather, countries will need to make their selection of topics in light of the considerations discussed above (United Nations, 1998, paragraph 2.9).

a. Household listing

41. Section A discussed two possible methods of data collection through censuses: complete enumeration and sample enumeration. There is the possibility, however, that some information will be collected through a household listing during the preparatory stage of a census operation. Some countries have included certain household characteristics during the mapping, house numbering and household listing stage, such as whether anyone in the household is engaged in agricultural activities, whether there is a handicraft or cottage industrial activity in the dwelling, or whether any member of the household has any disability or needs special care. These additional questions during the census preparatory stage attempt to accomplish two objectives: first, to reduce the burden in the census questionnaire and second, to collect information for the development of frames for future studies, either through complete coverage or sample surveys in the respective area. Many countries obtain information on household activities through the household listing stage of population censuses in preparation for their agricultural or economic censuses.

42. The main limitation of such an operation is the reliability of the information obtained, particularly for a rather difficult concept and definition, like disability. Often the data are collected from an informant or through observations, which may not reflect the correct situation. In addition, for certain topics, the frames obtained may become outdated in a short period of time. Naturally, to be successful, all census activities must be fully tested prior to finalizing them to ensure that the exercise will meet the intended objectives satisfactorily.

b. Census complete enumeration

Complete enumeration is the main important feature of a census. Any census must collect data on certain topics on a 100-per-cent basis. However, as mentioned earlier, many countries employ both complete and sample enumeration in a census. In a complete enumeration it is often difficult to institute and manage successful quality control measures, even if various techniques have been put in place, due to the fact that a large number of census workers are involved. When both complete and sample enumerations are used, it is necessary to ensure that topics collected through the complete enumeration are those which are of high priority, required at the lowest geographic level, and unreliable when estimated through sample enumeration due to either rare events or skewed distributions.

43. Countries that do not carry out a census sample enumeration should include basic demographic characteristics, education, economic activity and fertility and mortality questions in their census questionnaire. The minimum set of population topics, in addition to name and relationship to head or other member of household, that could be collected in the complete enumeration are: sex, age, marital status, citizenship, place of usual residence, place of birth, school attendance, educational attainment, activity status, occupation, industry, status of employment, children ever born and children living.

44. It is more difficult to determine a minimum set of housing and human settlement topics for housing censuses, due to the higher variability in housing characteristics among countries, than those in population. The three main items on buildings that are recommended to be included are type of building, construction material of outer walls and year or period of construction.

c. Census sample enumeration

45. Countries carrying out sample enumeration in conjunction with their censuses will be able to collect data on additional topics and ask more detailed questions using a long form. Depending on the need and ability of countries to include other information in the short form, basic economic and social characteristics may also be included in both forms, like school attendance, educational attainment, economic activity, place of birth, etc. Many countries also include on the long form all items collected in the short form. If these items are not included, it is very important to stress, that all items in the short form must be collected from all households.

46. The number and type of items that should be covered in the long form also depends on many factors including balance considerations mentioned in Section A and, more importantly, the fact that the census sample will not be able to provide estimates at the lowest geographic levels. Using a smaller number of enumerators who are better qualified and better trained will enable census organizations to carry out closer supervision and tighter quality control, which in the end should produce higher-quality data. While, as mentioned earlier, it is not recommended for any country to collect all items included in the list of topics of the UN census recommendations, potentially, all those items mentioned in the list can be collected through census sample enumeration.

d. Intercensal household survey

47. In Section A, it was recommended that countries should establish a continuing programme of household surveys as part of the overall national statistical data-collection system. In the area of demographic and social statistics, intercensal household surveys should constitute an integral part of this system. Many countries that carry out decennial censuses conduct at least one national demographic intercensal survey, often in the middle of the decade. In this survey, topics similar to those collected in the census sample enumeration are included. In addition, some countries may add special emerging topics that are needed by data users.

48. Other intercensal surveys include labour force surveys, socio-economic surveys, income, consumption and expenditure surveys, health surveys, etc. The timing and work programming in conducting such surveys should be coordinated with other statistical data-collection programmes.

2. Demographic and social statistics topics

49. In this section the scope of demographic and social statistics and their possible data sources will be presented in a table. Appendix 1 contains more detailed discussions on the definitions and recommendations on each item shown in Table 1. Appendix 1 also examines the advantages and disadvantages of each data source for various statistics with the aim of arriving at the most appropriate data sources for each of these statistics. Since compilation of demographic and social statistics is carried out by collecting the characteristics of individuals, households or living quarters, the table focuses on the characteristics or data items of individuals, households and living quarters. Cross-tabulation of these characteristics will provide the required statistics in the respective area designed to meet the need of the data users. Table 1 is organized as follows: (a) general demographic and social characteristics, (b) fertility and mortality, (c) geographical location and migration, (d) housing and human settlement, (e) education, (f) labour force, (g) time-use, (h) health, (i) disability, (j), income, consumption and expenditure, (k) food consumption and nutrition and (l) criminal justice.

a. General demographic and social characteristics (see Appendix 1, 1a-g)

50. General demographic characteristics of the individual, consisting of age, sex, relation to head or other reference member of household and marital status are the most important topics to be collected in any census. These topics at a minimum should be collected in a complete enumeration. Depending on the importance of social characteristics of the individual in the country, like citizenship, ethnicity, religion and languages in each individual country, these items can be collected through either complete enumeration or sample enumeration.

b. Fertility and mortality (see Appendix 1, 2a-h)

51. The importance of levels, trends, differentials and determinants of fertility and mortality for any country is well recognized. Children ever born and children living are the two priority items recommended under the fertility and mortality topics in the UN census recommendations as well as in the UN vital statistics recommendations. Many countries have included these items in their complete enumeration or at least in the sample enumeration. These items have also been the most important fertility and mortality questions to be collected through household demographic or fertility surveys.

52. Other fertility items included in the UN census recommendations are date of birth of last child born alive; deaths in the household during the past 12 months; survival of mother and/or father; age, date or duration of marriage; and age of mother at birth of first child born alive. Although some countries have included one or more of these topics in their complete enumeration, these items are considered more detailed fertility and mortality items that can be collected through either census sample enumeration or intercensal surveys. It is also recommended to record some of these items as mother’s characteristics in civil registration.

53. Studies show that the resulting statistics on “deaths in the household during the past 12 months” from censuses or surveys have not been reliable. Some countries have collected information on the “survival of natural mother and /or natural father” in an attempt to ascertain the level and patterns of mortality in the population. As mentioned above, these items are more appropriately collected through census sample or intercensal surveys. Countries with a complete civil registration can readily estimate the level of mortality and fertility in a particular area.

c. Geographic location and migration (see Appendix 1, 3a-g)

54.

CONTENTS

Summary