Hussain, S., and M. Elnajeh. “Prevalence and Risk Factors for Hypovitaminosis D Among Healthy Adolescents in Kota Bharu, Kelantan”. Journal of the ASEAN Federation of Endocrine Societies, Vol. 35, no. 2, Sept. 2020, https://asean-endocrinejournal.org/index.php/JAFES/article/view/867.