Akhter, N., F. Rahman, M. Salman, K. Anam, N. Begum, S. Naher, N. Fatema, Z. Hasan, M. Rashid, and S. Benerjee. “Valvular Heart Disease in Pregnancy: Maternal and Fetal Outcome”. Mymensingh Medical Journal, vol. 20, no. 3, Aug. 2011, pp. 436-40, https://www.banglajol.info/index.php/MMJ/article/view/8326.