Kozyra, Magdalena, Patryk Zimnicki, Justyna Kaczerska, Natalia Śmiech, Martyna Nowińska, and Joanna Milanowska. 2020. “The Effect of Vitamin D on Mental Health – Literature Analysis”. Journal of Education, Health and Sport 10 (8):398-407. https://doi.org/10.12775/JEHS.2020.10.08.048.