1. U S. Medical Eligibility Criteria for Contraceptive Use, 2010;Centers for Disease Control and Prevention (CDC);MMWR Recomm Rep,2010
2. U.S. Selected Practice Recommendations for Contraceptive Use, 2013: adapted from the World Health Organization Selected Practice Recommendations for Contraceptive Use, 2nd Edition;Division of Reproductive Health;MMWR Recomm Rep,2013
3. Centers for Disease Control and Prevention (CDC). U S. medical eligibility criteria for contraceptive use. 2010. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr59e0528a1.htm.
4. Accuracy of home pregnancy tests at the time of missed menses;Cole;Am J Obstet Gynecol,2004
5. Natural limits of pregnancy testing in relation to the expected menstrual period;Wilcox;JAMA,2001