1. Becker, G. (1960). An economic analysis of fertility. InDemographic and economic change in developed countries. A conference of the National Bureau of Economic Research. Princeton: Princeton University Press.
2. Bulatao, R. A. (1981). Values and disvalues of children in successive childbearing decisions.Demography, 18 2?26.
3. Coombs, L. C. & Chang, M. (1981). Do husbands and wives disagree? Fertility attitudes and later behavior.Population and Environment, 4 109?127.
4. Easterlin, R. A. (1969). Toward a socioeconomic theory of fertility. In S. J. Behrman, Leslie Corsa, Jr., & Ronald Freedman (Eds.),Fertility and family planning: A world view. Ann Arbor: The University of Michigan Press.
5. Espenshade, T. J. (1977).The value and cost of children.Population Bulletin, 32, (1). Washington: Population Reference Bureau, Inc.