Иржак, Л. И., Н. Г. Русских, and А. Н. Паршукова. “Variability of Time and Amplitude ECG Indicators in Older Adults”. Journal of Medical and Biological Research 9, no. 4 (December 7, 2021): 355–365. Accessed November 14, 2026. https://journals.narfu.ru/index.php/med/article/view/758.