1. Teenage sexual and reproductive behavior in developed countries;Darroch;Guttmacher Occasional Report,2001
2. Centers for Disease Control and Prevention (CDC). Trends in reportable sexually transmitted diseases in the United States, 2007. (http://www.cdc.gov/std/stats07/trends.htm#f1). (Accessed February 28, 2011).
3. WHO/ICO Information Centre on HPV and Cervical Cancer (HPV Information Centre). Human Papillomavirus and Related Cancers in World. Summary Report 2010. (www.who.int/hpvcentre). (Accessed May 11, 2013).
4. Disparities in rates of unintended pregnancy in the United States, 1994 and 2001;Finer;Persp Sex Reproduc Health,2006
5. Disparities in family planning;Dehlendorf;Am J Obstet Gynecol,2010