1. Sharing responsibility: women, society and abortion worldwide;Alan Guttmacher Institute,1999
2. Unintended pregnancy in sub-Saharan Africa: magnitude of the problem and potential role of contraceptive implants to alleviate it;Hubacher;Contraception,2008
3. The cost of unintended pregnancy in the United States;Trussell;Contraception,2007
4. World contraceptive use 2003;United Nations, Department of Economic and Social Affairs, Population Division,2003
5. Methods for the economic evaluation of health care programmes;Drummond,1987