Tindar, Mirzah, et al. “A Comparative Study of Nomegestrol Acetate and a Combination of Ethinylestradiol and Levonorgestrel for Delaying Menstruation Among Umrah Pilgrims”. Indonesian Journal of Obstetrics and Gynecology, vol. 6, no. 1, Jan. 2018, pp. 45-49, doi:10.32771/inajog.v6i1.757.