Zbalah, H. F., and B. A. Al-Zubaidi. “Investigation of Kisspeptin Hormone and Vitamin D3 Levels in Infertile Men”. International Journal of Health Sciences, vol. 6, no. S10, Oct. 2022, pp. 422-8, https://sciencescholar.us/journal/index.php/ijhs/article/view/13492.