Zhdan, V., M. Tkachenko, M. Babanina, Y. Kitura, and O. Kyrian. “The Most Common Causes of Comorbidity in Patients With Rheumatoid Arthritis”. Family Medicine, no. 4, Oct. 2021, pp. 79-83, doi:10.30841/2307-5112.4.2021.249428.