Villegas, A. E. (1987). A survey on the knowledge, attitude, and practice of family planning among population program professionals in Region XII. Socio-Economic Research Center, Notre Dame University.
Lua i Stíl Chicago (17ú heag.)Villegas, Alfonso E. A Survey on the Knowledge, Attitude, and Practice of Family Planning Among Population Program Professionals in Region XII. Cotabato City: Socio-Economic Research Center, Notre Dame University, 1987.
Lua MLA (8ú heag.)Villegas, Alfonso E. A Survey on the Knowledge, Attitude, and Practice of Family Planning Among Population Program Professionals in Region XII. Socio-Economic Research Center, Notre Dame University, 1987.
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