THE FREQUENCY OF USE OF COMBINATIONS OF ANTIHYPERTENSIVE DRUGS IN PATIENTS WITH DIFFICULT-TO-CONTROL HYPERTENSION ON THE BACKGROUND OF BIOFEEDBACK AND PACED BREATHING AND HEART RATE VARIABILITY. J. V. N. Karazin Khark. Nat. Univ., Ser. Med. 2018, No. 35. https://doi.org/10.26565/2313-6693-2018-35-09.