Anbreen, Tayyeba, et al. “Congenital Anomaly Frequency, Risk Factor and Trends Among Antenatal Patients Presenting at Tertiary Care Hospital in Pakistan”. Pakistan Journal of Medical Research, vol. 60, no. 2, July 2021, pp. 52-56, https://pjmr.org.pk/index.php/pjmr/article/view/143.