Piekarska, Ewa, Mateusz Pawlicki, Anna Łopuszyńska, Magdalena Kozioł, Aleksandra Krasa, and Halina Piecewicz-Szczęsna. 2021. “Association Between Male Fertility and Vitamin D”. Journal of Education, Health and Sport 11 (8):322-27. https://doi.org/10.12775/JEHS.2021.11.08.035.