Carr, SL; Gaffield, ME; Dragoman, MV; Phillips, S (tháng 9 năm 2016). “Safety of the progesterone-releasing vaginal ring (PVR) among lactating women: A systematic review”. Contraception. 94 (3): 253–61. doi:10.1016/j.contraception.2015.04.001. PMID25869631.
Carr, SL; Gaffield, ME; Dragoman, MV; Phillips, S (tháng 9 năm 2016). “Safety of the progesterone-releasing vaginal ring (PVR) among lactating women: A systematic review”. Contraception. 94 (3): 253–61. doi:10.1016/j.contraception.2015.04.001. PMID25869631.