Lentz G, Lobo RA, Gershenson D, Katz VL. Comprehensive Gynecology. 6th ed. Mosby Elsevier, 2013.
Hoffman B, Schorge JO, Bradshaw KD, et al. Williams Gynecology. 3rd ed. The McGraw Hill Companies, Inc. 2016.
Office on Women’s Health. US Department of Health and Human Services. Menstruation and the menstrual cycle Fact sheet. http://womenshealth.gov/publications/our-publications/fact-sheet/menstruation.html. Updated December 23, 2014. Accessed July 2016.