¹ See Gordon, Margaret, The Economics of Welfare Policies (New York: Columbia University Press, 1963)Google Scholar; Cutright, Phillips, “Political Structure, Economic Development and National Social Security Programs,” The American Journal of Sociology, 70 (03, 1965), 537–550 CrossRefGoogle Scholar; Cutright, Phillips, “Income Redistribution: A Cross-National Analysis,” Social Forces, 46 (12, 1967), 180–190 CrossRefGoogle Scholar; Aaron, Henry, “Social Securitv: International Comparisons,” in Eckstein, Otto, ed., Studies in the Economics of Income Maintenance (Washington, D.C.: The Brookings Institution, 1967)Google Scholar; Pryor, Frederick, Public Expenditures in Communist and Capitalist Nations (Homewood, Ill.: George Allen and Unwin, Ltd., 1968)Google Scholar; and Taira, Koji and Kilby, Peter, “Differences in Social Security Development in Selected Countries,” International Social Security Review, 22 (1969), 139–153 CrossRefGoogle Scholar.

² In quantitative research, the only exception of which we are aware is a two and a half page analysis in Appendix E-12 in Pryor, Public Expenditures. Historical studies such as Rimlinger, Gaston V., Welfare Policy and Industrialization in Europe, America and Russia (New York: John Wiley & Sons, 1971)Google Scholar have also attempted to explain timing of adoption.

³ This expression is used loosely here to refer to what Marion Levy has labeled functional and structural prerequisites. In using the expression prerequisites, we are following his distinction between the prerequisites for the appearance of a given phenomenon and the requisites for its continued existence. See Levy, Marion J. Jr., The Structure of Society (Princeton: Princeton University Press, 1952), pp. 62–63 and 71–72 Google Scholar.

⁴ Examples of cross-national studies that examine various forms of the prerequisites and requisites hypotheses (see footnote 3) with regard to democratic political outcomes are Lipset, S. M., “Some Social Requisites of Democracy: Economic Development and Political Legitimacy,” American Political Science Review, 53 (03, 1959), 69–105 CrossRefGoogle Scholar; Coleman, James S., “Conclusion: The Political Systems of the Developing Areas,” in Almond, Gabriel A. and Coleman, James S., eds., The Politics of the Developing Areas (Princeton: Princeton University Press, 1960) pp. 532–576 Google Scholar; Hagen, Everett E., “A Framework for Analyzing Economic and Political Change,” in Development of the Emerging Countries, ed. Asher, Robert E. et al. (Washington, D.C.: The Brookings Institution, 1962) pp. 1–38 Google Scholar; Cutright, Phillips, “National Political Development: Measurement and Analysis,” American Sociological Review, 28 (04, 1963), 253–264 CrossRefGoogle Scholar; Simpson, Dick, “The Congruence of Political, Social, and Economic Aspects of Development,” International Development Review, 6 (06, 1964), 21–25 Google Scholar; Alker, Hayward R. Jr., “Causal Inference in Political Analysis,” in Bernd, Joseph, ed., Mathematical Applications in Political Science, Il. Arnold Foundation Monographs, XVI (Dallas: Southern Methodist University Press, 1966) pp. 7–37 Google Scholar; Neubauer, Deane E., “Some Conditions of Democracy,” American Political Science Review, 61 (12, 1967), 1002–1009 CrossRefGoogle Scholar; Olsen, Marvin E., “Multivariate Analysis of National Political Development,” American Sociological Review, 33 (10, 1968), 699–712 CrossRefGoogle Scholar; Cutright, Phillips and Wiley, James A., “Modernization and Political Representation: 1927–1966,” Studies in Comparative International Development, 5 (1969–1970)CrossRefGoogle Scholar. For studies in this tradition using political participation as a dependent variable, see Lerner, Daniel, The Passing of Traditional Society (Glencoe, Ill.: The Free Press, 1958)Google Scholar; Hayward Alker, “Causal Inference in Political Analysis”; McCrone, Donald J. and Cnudde, Charles F., “Toward a Communications Theory of Democratic Political Development: A Causal Model,” American Political Science Review, 61 (03, 1967), 72–79 CrossRefGoogle Scholar.

⁵ References to the idea of diffusion may be found in much political research (see, for example, Almond, Gabriel and Verba, Sidney, The Civic Culture (Boston: Little, Brown and Company, 1965), p. 2 Google Scholar, but the number of studies that have presented explicit tests for diffusion is limited. These have included Rice, Stewart A., Quantitative Methods in Politics (New York: Alfred Knopf, 1928)Google Scholar; Crain, Robert L., “Fluoridation: The Diffusion of an Innovation Among Cities,” Social Forces, 44 (06, 1966), 467–476 CrossRefGoogle Scholar; Putnam, Robert D., “Toward Explaining Military Intervention in Latin American Politics,” World Politics, 20 (10, 1967), 102–3CrossRefGoogle Scholar; Walker, Jack L., “The Diffusion of Innovations Among the American States,” The American Political Science Review, 63 (09, 1969), 880–899 CrossRefGoogle Scholar; Midlarsky, Manus, “Mathematical Models of Instability and a Theory of Diffusion,” International Studies Quarterly, 14 (11, 1970), 60–84 CrossRefGoogle Scholar. For a discussion of systematic attempts to examine the role of diffusion in social security adoption, see the discussion later in this article. The literature on diffusion outside of political science is usefully summarized by Rogers, Everett M. and Shoemaker, F. Floyd, Communication of Innovations, 2nd ed. (New York: The Free Press, 1971)Google ScholarPubMed and Hudson, John C., Geographical Diffusion Theory (Evanston, Ill., Northwestern University, Department of Geography, 1972)Google Scholar.

⁶ See Naroll, Raoul, “Galton's Problem: The Logic of Cross-Cultural Research,” Social Research, 32 (Winter, 1965), 428–451 Google Scholar; Brian J. L. Berry, “Some Methodological Consequences of Using the Nation as a Unit of Analysis in Comparative Politics,” paper prepared for the Committee on Comparative Politics of the Social Science Research Council, 1970; John V. Gillespie, “Galton's Problem and Parameter Estimation Error in Comparative Political Analysis,” paper prepared for delivery at the Annual Meeting of the Midwest Political Science Association, Chicago, 1970; and Richard E. Hildreth and Raoul Naroll, “Galton's Problem in Cross-National Studies,” paper prepared for the Committee on Comparative Politics of the Social Science Research Council, 1970.

⁷ Berry has made this point with particular reference to spatial diffusion. He has argued that whereas “in time series a natural distinction exists between past and future, no such property characterizes spatial series. Dependence will extend in a variety of directions, and often on vectors at angles to the Cartesian grid, leading to elaborate cross-product locational terms…. [M]ost of the functions introduced by statisticians into the field of spatial processes have been introduced simply because the mathematics exists, as extensions of time-series analysis, without thought for their usefulness or interpretability. And even more significant, all of the existing models rely on an assumption of stationarity, i.e., that the relation between values of the processes is the same for every pair of points whose relative positions are the same. This is patently invalid.” See Berry, Brian J. L., “Problems of Data Organization and Analytical Methods in Geography,” Journal of the American Statistical Association, 36 (09, 1971), 521 Google Scholar.

⁸ See Bodenheimer, Susanne J., The Ideology of Developmentalism: The American Paradigm-Surrogate for Latin American Studies. Sage Professional Papers in Comparative Politics, Vol. 2 (Beverly Hills, Cal.: Sage Publications, 1971), pp. 22ffGoogle Scholar and A. Eugene Havens, “Methodological Issues in the Study of Development,” paper prepared for delivery at them Third World Congress of Rural Sociology, Baton Rouge, Louisiana, August, 1972.

⁹ See Rostow, W. W., The Stages of Economic Growth (London: Cambridge University Press, 1960), p. 38 Google Scholar, and Politics and the Stages of Growth (London: Cambridge University Press, 1971), p. 55 Google Scholar; Black, C. E., The Dynamics of Modernization: A Study in Comparative History (New York: Harper and Row, 1966), pp. 90ffGoogle Scholar; Banks, Arthur S. and Textor, Robert B., A Cross-Polity Survey (Cambridge: The M.I.T. Press, 1963), pp. 78–80 Google Scholar; Barsby, Steven L., “Economic Backwardness and the Characteristics of Development,” Journal of Economic History, 29 (09, 1969), 449–473 CrossRefGoogle Scholar; Cardoso, Fernando H. and Reyna, Jose Luis, “Industrialization, Occupational Structure, and Social Stratification in Latin America” in Constructive Change in Latin America, ed. Blasier, Cole (Pittsburgh: University of Pittsburgh Press, 1968), pp. 25–26 Google Scholar; and Collier, David, “Timing of Economic Growth and Regime Characteristics in Latin America,” Comparative Politics, 7 (04, 1975), 331–360 CrossRefGoogle Scholar.

¹⁰ ” See, for instance, Nordlinder, Eric A., “Political Development: Time Sequences and Rates of Change,” World Politics, 20, No. 3 (04, 1968), 494–520 CrossRefGoogle Scholar; Heintz, Peter, Ein Soziologisches Paradigma der Entwicklung (Stuttgart, Ferdinand Enke Verlag, 1969)Google Scholar; Pride, Richard A., Origins of Democracy: A Cross-National Study of Mobilization, Party Systems and Democratic Stability, Sage Professional Papers in Comparative Politics Vol. 1 (Beverly Hills, Cal.: Sage Publications, 1970)Google Scholar; Verba, Sidney, “Sequences and Development, in Crises and Sequences in Political Development, ed. Binder, Leonard et al. (Princeton: Princeton University Press, 1971), pp. 283–316 Google Scholar; Dahl, Robert A., Polyarchy (New Haven: Yale University Press, 1971)Google Scholar; Flanigan, William and Fogleman, Edwin, “Patterns of Political Development and Democratization: A Quantitative Analysis,” in Macro-Quantitative Analysis, ed. Gillespie, John V. (Beverly Hills, Cal.; Sage Publications, 1971), pp. 441–473 Google Scholar and “Patterns of Democratic Development: An Historical Comparative Analysis,” in Gillespie, and Nesvold, , pp. 475–497 Google Scholar.

¹¹ This is a paraphrase of the definition found in U.S. Department of Health, Education and Welfare, Social Security Administration, Social Security Programs Throughout the World, 1971 (Washington, D.C.: Government Printing Office, 1971), p. ix Google Scholar.

¹² For a detailed discussion of the early development of social security, see Rys, Vladmir, “The Sociology of Social Security,” Bulletin of the International Social Security Association, 17, No. 1 (January-February, 1964), 3–34 Google Scholar; and Rimlinger, Welfare Policy and Industrialization.

¹³ Rys, , “The Sociology of Social Security,” p. 6 Google Scholar.

¹⁴ Baernreither, J. M., English Associations of Working Men (London: Swan Sonnenschein & Co., 1889, republished in 1966 by Gale Research Company, Detroit), p. 165 Google Scholar.

¹⁵ U.S. Department of Commerce and Labor, Twenty-Fourth Annual Report of the Commissioner of Labor, 1909. Workmen's Insurance and Compensation Systems in Europe (Washington, D.C.: U.S. Government Printing Office, 1911), p. 8 Google Scholar.

¹⁶ Woodbury, Robert Morse, Social Insurance: An Economic Analysis (New York: Henry Holt & Co., 1917), p. 8 Google Scholar.

¹⁷ These and other dates are from U.S. Department of Health, Education, and Welfare, Social Security Programs.

¹⁸ For an excellent discussion of this phenomenon of gradual growth in Latin America see “Gradual Extension of Social Insurance Schemes in Latin American Countries,” International Labour Review, 68 (09, 1958), 257–283 Google Scholar.

¹⁹ U.S. Department of Health, Education, and Welfare (Washington, D.C.: U.S. Government Printing Office, 1971). The limitations of this source are discussed in the Appendix.

²⁰ See Aaron, “Social Security”; Fredrick Pryor, Public Expenditures; Taira and Kilby, “Differences in Social Security Development:” and Cutright, “Political Structure, Economic Development and National Social Security Programs” and “Income Redistribution.”

²¹ The procedure followed here is that recommended by Przeworski and Teune for confirming the reliability of an indicator. See Adam Przeworski, and Teune, Henry, The Logic of Comparative Social Inquiry (New York: John Wiley and Sons, 1970), pp. 114–115 Google Scholar.

²² Cutright, , “Political Structure, Economic Development and National Social Security,” p. 540 Google Scholar.

²³ See Richardson, J. Henry, Economic and Financial of Aspects of Social Security: An International Survey (Toronto: University of Toronto Press, 1960), pp. 139–155 Google Scholar for a discussion of the issues involved in family allowance programs.

²⁴ See Cutright, “Income Redistribution;” Aaron, “Social Security”; Pryor, Public Expenditures; and Taira and Kilby, “Differences in Social Security Development.” It should be noted that whereas these correlations are treated, in the present research as a means of assessing the validity of an indicator these authors have used them to examine causal relations among different aspects of social security experience.

²⁵ The negative sign of this correlation and the two others reported in the next paragraph results from the fact that timing of adoption is measured by the year of adoption, and hence involves a smaller number for the earlier adopters. The measure of spending is taken from The Cost of Social Security, published by the International Labor Organization (Geneva: 1967)Google Scholar.This correlation is based on data on 34 countries.

²⁶ The data on coverage are taken from International Labor Office The Yearbook of Labor Statistics, 1961 (Geneva, 1961)Google Scholar. The correlation for work injury is based on 27 cases, and that for pensions on 30 cases.

²⁷ Probably the most important aspect of social I security development—the quality of the benefits offered to those who are covered—is extremely difficult to measure. One might hypothesize that timing of adoption and quality of services are strongly associated, but that as one moves from earlier to later adopters, the lag between the first adoption of programs and the growth in the quality of programs would be greater and greater. Wolf's discussion of the quality of services in Latin America—a region in which the first adoption occurred nearly three decades after the first adoption in Germany—would appear to support this hypothesis. He suggests that dilution of the quality of service, long delays in insurance payments, wide-spread corruption and bribery are found even in the most advanced countries in Latin America. See Wolfe, Marshall, “Social Security and Development: The Latin American Experience,” in The Role of Social Security in Economic Development, ed. Kassalow, Everett M. (Washington, D.C.: U.S. Department of HEW, Social Security Administration, Research Report No. 27, 1968), pp. 155 and 165 Google Scholar.

²⁸ Pryor, , Public Expenditures, pp. 134–135 Google Scholar.

²⁹ For a useful discussion of the literature that has overstated the importance of the transition for rural to urban life, see Cornelius, Wayne A. Jr., “The Political Sociology of Cityward Migration in Latin America: Toward an Empirical Theory,” in Latin American Urban Research, I, Rabinovitz, Francine F. and Trueblood, Felicity M., eds. (Beverly Hills, Cal., Sage Publications, 1971) pp. 95–150 Google Scholar. In the present context it is important to note that opportunities for non-monetary provisions of certain types may be present in cities. See, for instance, Mangin's, William “Latin American Squatter Settlements: A Problem and a Solution,” Latin American Research Review, 2, No. 3 (Summer, 1967), 65–98 Google Scholar.

³⁰ Cutright, , “Income Redistribution,” p. 184 Google Scholar.

³¹ Organski, A. F. K., The Stages of Political Development (New York: Alfred K. Knopf, 1965), p. 162 Google Scholar.

³² Pryor, , Public Expenditures, p. 474 Google Scholar.

³³ Ibid., pp. 145–146 and Taira, and Kilby, , “Differences in Social Security Development,” p. 142 Google Scholar.

³³ Pryor, p. 146.

³⁴ Ibid., p. 135.

³⁵ Rimlinger, , Welfare Policy and Industrialization, p. 209 Google Scholar.

³⁷ Aaron, , “Social Security,” pp. 32–33 Google Scholar.

³⁸ See Rimlinger, pp. 103–104.

³⁹ Galenson, Walter, “Social Security and Economic Development: A Quantitative Approach,” Industrial and Labor Relations Review, Vol. 21, No. 4 (07, 1968), 559–569 CrossRefGoogle Scholar.

⁴⁰ Rimlinger, Gaston V., “Welfare Policy and Economic Development: A Comparative Historical Perspective,” Journal of Economic History, 26 (12, 1966), 568 CrossRefGoogle Scholar.

⁴¹ Rys, , “The Sociology of Social Security,” p. 4 Google Scholar.

⁴² U.S. Department of Commerce and Labor, 24th Annual Report, pp. 1862-1863 and Klumpar, V., “The Investment of Social Insurance Funds,” International Labor Review, 27 (01, 1933), 53 Google Scholar.

⁴³ U.S. Department of Commerce and Labor, 24th Annual Report, p. 44.

⁴⁴ Jones, Thomas, Lloyd George (Cambridge, Mass.: Harvard University Press, 1951), pp. 36–37 CrossRefGoogle Scholar.

⁴⁵ U.S. Department of Commerce and Labor, 24th Annual Report, p. xv. The National Association of Manufacturers sent a group to Germany in 1909 to study the social insurance system there, and the Russell Sage Foundation also sponsored a study of European systems of social insurance in 1908. See Rimlinger, , “Welfare Policy and Economic Development,” p. 566 Google Scholar and Frankel, Lee K. and Dawson, Miles M., Workingmen's Insurance in Europe, (New York: Russell Sage Foundation, 1910)Google Scholar.

⁴⁶ U.S . Department of Commerce and Labor, 24th Annual Report, p. 25.

⁴⁷ Craig, Isabel and Tomes, Igor, “Origins and Activities of the ILO Committee of Social Security Experts,” International Social Security Review, 22 (1969), 509 CrossRefGoogle Scholar.

⁴⁸ Pilcher, Donald M., Ramirez, Charles J., and Swihart, Judson J., “Some Correlates of Normal Pensionable Age,” International Social Security Review, 21, 3 (1968), 387–411 CrossRefGoogle Scholar.

⁴⁹ Taira, and Kilby, , “Differences in Social Security Development,” p. 143 Google Scholar.

⁵⁰ See Berry, “Problems of Data Organization,” and Berry, and Neils, Elaine, “Location, Size and Shape of Cities as Influenced by Environmental Factors: The Urban Environment Writ Large,” in The Quality of the Urban Environment, Perloff, Harvey S., ed. (Washington, D.C.: Resources for the Future, Inc., 1971)Google Scholar; Tilton, John E., International Diffusion of Technology: The Case of Semiconductors (Washington: The Brookings Institution, 1971)Google Scholar; Walker, “The Diffusion of Innovations Among the American States”; Crain, , “Fluoridation,” p. 572 Google Scholar; and Pedersen, Paul O., “Innovation Diffusion Within and Between National Urban Systems,” Geographical Analysis (07, 1970), pp. 203–254 Google Scholar.

⁵¹ Rogers, and Shoemaker, , Communication of Innovations, p. 186 Google Scholar.

⁵² Walker, , “The Diffusion of Innovations,” p. 885 Google Scholar.

⁵³ The expression positioning behavior was suggested by Jack Walker in a personal communication.

⁵⁴ Katz, Elihu and Lazarsfeld, Paul F., Personal Influence (Glencoe, III.: The Free Press, 1955)Google Scholar and Matthews, Donald R. and Stimson, James A., “Decision-Making by U.S. Representatives: A Preliminary Model,” in Political Decision-Making, ed. Ulmer, S. Sidney (New York: Van Nostrand Reinhold Co., 1970), pp. 22–23 Google Scholar.

⁵⁵ Even such outstanding sources as Rokkan, Stein and Meyriat, Jean, International Guide to Electoral Statistics, Vol. 1: National Elections in Western Europe (The Hague: Mouton, 1969)Google Scholar, a major source of data on electoral participation, do not provide data on variables such as the proportion of the population voting in elections for enough countries at the appropriate points in time to permit any meaningful analysis.

⁵⁶ This coefficient is derived from the Economic Report of the President, 1972 (Washington, D.C.: U.S. Government Printing Office, 1973), pp. 247–253 Google Scholar.

⁵⁷ This method of illustrating the relationship between development and timing of adoption is similar to that used by quantitative geographers who have analyzed the diffusion of innovations among urban centers by plotting size of urban center at the time of adoption by the year of adoption for various types of innovations. See Berry, , “Problems of Data Organization and Analytical Methods in Geography,” p. 521 Google Scholar; Berry, and Neils, , “Location, Size, and Shape of Cities,” p. 299 Google Scholar; and Pedersen, , “Innovation Diffusion Within and Between National Urban Systems,” pp. 209–212 Google Scholar.

⁵⁸ Although there is considerable disagreement about the relevance of tests of significance for interpreting correlations in nonsample data, we will present them for readers who find them useful. These correlations for work force in agriculture and work force in industry are significant at the .01 level. That for real income is significant at the .02 level.

⁵⁹ Rys, Vladmir, “Comparative Studies of Social Security: Problems and Perspectives,” Bulletin of the International Social Security Association, Nos. 7-8 (July-August, 1966), 242–268, at p. 245Google Scholar.

⁶⁰ Lund, Michael S., Comparing the Social Policies of Nations: A Report on Issues, Methods, and Resources (Center for the Study of Welfare Policy, University of Chicago, 1972), p. 42 Google Scholar.

⁶¹ Johnson, Harry, ed. Economic Nationalism in Old and New States (Chicago: University of Chicago Press, 1967), pp. 1ffGoogle Scholar.

⁶² See Gerschenkron, Alexander, “Economic Back-wardness in Historical Perspective,” in The Progress of the Underdeveloped Countries, ed. Hoselitz, Bert F. (Chicago: University of Chicago Press, 1952), pp. 3–29 Google Scholar and Dahrendorf, Ralf, Society and Democracy in Germany (Garden City: Doubleday and Co., 1967)Google Scholar.

⁶³ On the basis of data made available to the senior author by the Ministry of Labor in Peru, the earliest date of foundation of the mutual benefit associations which have received government recognition in that country is around 1900, only a few years before the first adoption of social security. Although there may have been other associations which were founded much earlier, this suggests at least tentatively that these associations had a far more limited development prior to the appearance of social security than in Europe.

⁶⁴ Lampman, Robert J., “The Investment of Social Security Reserves and Development Problems: The Philippines as a Case History,” in The Role of Social Security in Economic Development, ed. Kassalow, , pp. 92–93 Google Scholar.

⁶⁵ The importance of social security in weakening labor movements has been suggested in Gaston V. Rimlinger, “Social Security and Industrialization: The Western Experience, with Possible Lessons for the Less Developed Nations,” in Kassalow, , The Role of Social Security in Economic Development, pp. 135 and 143 Google Scholar and in Chaplin, David, The Peruvian Industrial Labor Force (Princeton: Princeton University Press, 1967), p. 78 Google Scholar. The remarkable history of resistance to the adoption of national unemployment insurance in the United States by the American Federation of Labor also illustrates the importance of the threat posed to labor movements by social security. See McConnell, Grant, Private Power and American Democracy (New York: Alfred A. Knopf, 1966), p. 85 Google Scholar.

⁶⁹ The correlations for work force in industry and real income for these countries are .34 and .22 respectively, with slight increases if Germany and the United Kingdom are removed.

⁶⁷ A close analogue to this pattern of diffusion may be found in social psychological discussions of marginal individuals as innovators. See Rogers, Everett M., Diffusion of Innovations (New York: The Free Press, 1962)Google Scholar, chapter 7. In “The Diffusion of Innovations…,” p. 883, Walker notes that Mississippi was the first state in the United States to adopt a general sales tax. This is not surprising, in light of the fact that this is a regressive tax. However, Walker does not report the pattern of adoption for this innovation following its introduction in Mississippi.

⁶⁸ Rimlinger, , Welfare Policy and Industrialization, pp. 35ff and 93–98 Google Scholar.

⁶⁹ See the Gerschenkron and Dahrendorf references cited in footnote 62 above.

⁷⁰ Berry, and Neils, , “Location, Size, and Shape of Cities' as Influenced by Environmental Factors,” p. 298 Google Scholar, have used a somewhat similar mapping procedure to illustrate the spatial diffusion of street cars in the United States.

⁷¹ These correlations are significant at the .01, .01, and .20 levels respectively. The correlations presented in the following paragraph are all significant at the .01 level.

⁷² The first involves ambiguity with regard to the year of adoption by the United States, which might be scored around 1920 because of the extensive development of work injury programs at the state level by that date (see Appendix). Though the date that was used for the United States does not make much difference in the correlations presented earlier, it places the United States in the group of late adopters and has a considerable effect on the correlations within this group. The other outlier is Libya in the correlation involving real income. Libya adopted at a far higher level of income than would be expected because it was already a major exporter of oil at the time of adoption. It might be argued that real income is a particularly misleading indicator of development for Libya.

⁷³ United States Department of Health, Education, and Welfare, Social Security Programs Throughout the World, 1971. The only nations not reporting to the Social Security Administration were Guinea, Fiji, Kuwait, Lesotho, Maldive Islands, Nepal, North Korea, and Southern Yemen.

⁷⁴ This point is made by Rys, Vladmir, “Some Current Problems of Social Security in the World,” Bulletin of the International Social Security Association, 21 (1968), 432–442, at p. 439CrossRefGoogle Scholar.

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