Victor , Arne, Hans Lithell, lngemar Selinus, and Bengt Vessby. “Pharmacodynamics of a Contraceptive Vaginal Ring Releasing Norethindrone and Estradiol: Ovarian Function, Bleeding Control and Lipoprotein Patterns”. Upsala Journal of Medical Sciences 89, no. 2 (June 1, 1984): 179-188. Accessed March 25, 2026. https://ujms.net/index.php/ujms/article/view/7023.