Shrestha, N. S., S. Pande, M. Joshi, and S. Padhye. “Primary Umbilical Endometriosis A Case Report”. Nepal Journal of Obstetrics and Gynaecology, vol. 6, no. 1, Aug. 2011, pp. 51-52, https://www.nepjol.info/index.php/NJOG/article/view/5253.