Vovkanych, L., Y. Boretsky, V. Sokolovsky, D. Berhtraum, and S. Kras. “Validation of the Software-Hardware Complex ‘Rytm’ for Measurement of the RR Intervals and Heart Rate Variability Analysis During Exercise and Recovery Period”. Physical Education Theory and Methodology, vol. 21, no. 1, Mar. 2021, pp. 61-68, doi:10.17309/tmfv.2021.1.08.