1. Singh S, Darroch JE, Ashford LS, Vlassoff. The costs and benefits of investing in family planning and maternal and newborn health. New York: Guttmacher Institute and UNFPA, 2009. www.guttmacher.org/pubs/AddingItUp2009.pdf (accessed 22 March 2010).
2. Unintended pregnancy in sub-Saharan Africa: magnitude of the problem and potential role of contraceptive implants to alleviate it
3. Smith R, Ashford L, Gribble J. Family Planning Saves Lives, 4th edition, 2009. www.prb.org/Reports/2009/fpsl.aspx