Brache, V, Sitruk-Ware, R, Williams, A, Blithe, D, Croxatto, H, Kumar, N, Kumar, S, Tsong, Y-Y, Sivin, I, Nath, A, Sussman, H, Cochon, L, Miranda, M J, Reyes, V, Faundes, A & Mishell, D 2012, ' Effects of a novel estrogen-free, progesterone receptor modulator contraceptive vaginal ring on inhibition of ovulation, bleeding patterns and endometrium in normal women ', Contraception, vol. 85, no. 5, pp. 480-8 . https://doi.org/10.1016/j.contraception.2011.10.003