Khan, Muhammad Alamgir, M Mazhar Hussain, and Shoaib Bin Aleem. “HEART RATE VARIABILITY IN HEALTHY POPULATION”. Pakistan Journal of Physiology 6, no. 2 (December 31, 2010): 40–42. Accessed April 24, 2024. https://pjp.pps.org.pk/index.php/PJP/article/view/807.