Hanna M. Aboulghar, Khalil AbdElkhalek, Sara S. El Tatawy, Yomna M. Shalan, Christine G. Salama. “Vitamin D Deficiency Among Preschool Children and Its Correlation With Nutritional Habits and Sun Exposure”. Annals of the Romanian Society for Cell Biology (May 13, 2021): 4228–4237. Accessed April 3, 2026. http://annalsofrscb.ro/index.php/journal/article/view/5245.