Vitamin D levels and oxidative stress markers in patients hospitalized with COVID-19 - Atanasovska, Emilija; Petrushevska, Marija; Zendelovska, Dragica; Spasovska, Katerina; Stevanovikj, Milena; Kasapinova, Katerina; GJorgjievska, Kalina; Labachevski, Nikola (Taylor and Francis (United Kingdom), 2021)