Бабак, В. П., and О. В. Чілікин. “Application of the Principal Components Method for the Analysis of Heart Rate Variability”. Proceedings of National Aviation University (archive) 18, no. 3-4 (May 5, 2021): 3–7. Accessed April 13, 2026. http://jrnl.nau.edu.ua/index.php/visnik/article/view/15349.