Navi Khan, Gul Ar, Nazia Ishrat, and Zulquarnain . 2017. “Analysis of Heart Rate Variability in Pre-Eclamptic Pregnancy: A Study Employing Frequency Domain Analysis”. International Journal of Reproduction, Contraception, Obstetrics and Gynecology 3 (4):1037-42. https://www.ijrcog.org/index.php/ijrcog/article/view/2223.