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2. “Birth order, family size, and intelligence.”;Belmont;Science,1973
3. “Coercive pronatalism and American population policy.”;Blake,1972
4. “Three generations of parents.”;Campbell;Family Planning Perspectives,1973
5. Easterlin, Richard A. 1962 “The American baby boom in historical perspective.” Occasional paper No. 79, National Bureau of Economic Research.