Belal, S. A. S., E. O. Nazarenko, A. O. Radchenko, A. L. Kulik, A. V. Martynenko, and N. I. Yabluchansky. 2015. “IVABRADINE AND QUALITY OF BIOFEEDBACK IN THE LOOP OF PACED BREATHING UNDER THE CONTROL OF HEART RATE VARIABILITY PARAMETERS IN HEALTHY VOLUNTEERS”. The Journal of V. N. Karazin Kharkiv National University, Series "Medicine", no. 25 (July), 13-16. https://periodicals.karazin.ua/medicine/article/view/3394.