Hishamuddin, Nurin Asyiqin, and Mohd Hezri Mokhtar. “Development of Heart Rate Variability Analysis Device for Human Body Stress Level Indication”. Progress in Engineering Application and Technology 5, no. 1 (June 10, 2024): 213–219. Accessed April 7, 2026. https://publisher.uthm.edu.my/periodicals/index.php/peat/article/view/14762.