1. Contraceptive methods women have ever used: United states, 1982‐2010;Daniels K;Natl Health Stat Report,2013
2. Oral contraceptives containing drospirenone for premenstrual syndrome;Lopez LM;Cochrane Database Syst Rev,2012
3. Intrauterine Contraception
4. FDA approves new vaginal ring for one year of birth control. US Food and Drug Administration website.https://www.fda.gov/news-events/press-announcements/fda-approves-new-vaginal-ring-one-year-birth-control. August 10 2018. Accessed September 24 2018.