For citations:
Ovsyannikov E.S., Avdeev S.N., Budnevskiy A.V., Drobysheva E.S., Kravchenko A.Ya. COVID-19 and chronic obstructive pulmonary disease: what is known about the unknown. Tuberculosis and Lung Diseases. 2021;99(2):6-15. (In Russ.) https://doi.org/10.21292/2075-1230-2021-99-2-6-15