Tabitha, S., and M. Rajini. “The Study of Arterial and Venous Doppler in High Risk Pregnancies and Its Role in Perinatal Outcome”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology, vol. 7, no. 3, Feb. 2018, pp. 1116-22, doi:10.18203/2320-1770.ijrcog20180904.