1. Ross JA, Parker W, Gree SR et al. Family planning and child survival programs as assessed in 1991. The Population Council, New York, 1992.
2. Ratnam SS, Loh FH, Prasad RNV. Oral contraceptives in developing countries. Adv Contracept. 1991;7(1):55–6.
3. Wharton C, Blackburn R. Lower dose pills. In: Rinehart W, ed. Population Reports, Series A, No. 7. Baltimore, John Hopkins University. Population Information Program, 1988.
4. Hawker-Costa S, Ramos M, Regina S. Family planning among low-income women in Rio de Janeiro: 1984–1985. Int Fam Plann Perspect. 1990;16(1):16–22.
5. Profamilia DHS. Colombia, encuesta de prevalencia, demografía y salud, 1990. Santafé de Bogotá, 1991.