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Audet MC, Moreau M, Koltun WD, Waldbaum AS, Shangold G, Fisher AC, Creasy GW (2001). «Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive: a randomized controlled trial» (Slides of comparative efficacy]). JAMA 285 (18): 2347-54. doi:10.1001/jama.285.18.2347. PMID 11343482. http://www.contraceptiononline.org/slides/slide01.cfm?q=pearl+index&dpg=6Архивная копия от 26 марта 2007 на Wayback Machine. Guttmacher Institute. «Contraceptive Use». Facts in Brief. Guttmacher Institute. Retrieved on 2005-05-10. — see table First-Year Contraceptive Failure Rates
Amir H. Mehryar, A. Aghajanian, B. Delavar, H. Eini-Zinab, & Shahla Kazemipour (2005). Continuing use of a traditional method (withdrawal) in a high contraceptive prevalence country, Iran: Correlates and consequences. Ministry of Science, Research and Technology, Iran. Архивированная копия (неопр.). Дата обращения: 23 сентября 2006. Архивировано 1 сентября 2006 года.. Retrieved on 2006-09-14.
Audet MC, Moreau M, Koltun WD, Waldbaum AS, Shangold G, Fisher AC, Creasy GW (2001). «Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive: a randomized controlled trial» (Slides of comparative efficacy]). JAMA 285 (18): 2347-54. doi:10.1001/jama.285.18.2347. PMID 11343482. http://www.contraceptiononline.org/slides/slide01.cfm?q=pearl+index&dpg=6Архивная копия от 26 марта 2007 на Wayback Machine. Guttmacher Institute. «Contraceptive Use». Facts in Brief. Guttmacher Institute. Retrieved on 2005-05-10. — see table First-Year Contraceptive Failure Rates
Amir H. Mehryar, A. Aghajanian, B. Delavar, H. Eini-Zinab, & Shahla Kazemipour (2005). Continuing use of a traditional method (withdrawal) in a high contraceptive prevalence country, Iran: Correlates and consequences. Ministry of Science, Research and Technology, Iran. Архивированная копия (неопр.). Дата обращения: 23 сентября 2006. Архивировано 1 сентября 2006 года.. Retrieved on 2006-09-14.