Willis SK, Mathew HM, Wise LA, Hatch EE, Wesselink AK, Rothman KJ, Mahalingaiah S. Menstrual patterns and self-reported hirsutism as assessed via the modified Ferriman-Gallwey scale: a cross-sectional study. Eur J Obstet Gynecol Reprod Biol. 2020 May 1;248:137-43. doi: 10.1016/j.ejogrb.2020.03.012