Walczak, K., Walczak, P., Zdun, S., Nemeczek, S., Merkisz, K., Grzybowski, J., … Orłowski, W. (2023). Effect of vitamin D on the course of COVID-19 infection. Journal of Education, Health and Sport, 13(2), 261–267. https://doi.org/10.12775/JEHS.2023.13.02.038