Shchedrina Yu.A., Melnikov D.S., and Pavlenko A.V. “TEMPORAL AND SPECTRAL INDICATORS OF HEART RATE VARIABILITY OF TAEKWONDO ATHLETES”. Theory and Practice of Physical Culture, no. 9, Sept. 2023, pp. 57-59, http://tpfk.ru/index.php/TPPC/article/view/679.