MARZEC, Jakub, ŁUKASZ, Krzysztof, MUSIOŁ, Aleksandra, GWAŁT, Paweł, NOWAKOWSKI, Michał and RAKUŚ, Magdalena. Role of vitamin D supplementation in the prevention of URTI (upper respiratory tract infections) among highly physically active individuals. Journal of Education, Health and Sport. Online. 7 April 2026. Vol. 89, p. 70263. [Accessed 10 April 2026]. DOI 10.12775/JEHS.2026.89.70263.