El Sawy, I. H., P. A.-S. Moaz, G. M. Farouk El Deriny, and M. S. Abd El Moniem El Kholy. “Serum 25-Hydroxy Vitamin D in Asthmatic Children and Its Relation to Disease Severity”. International Journal Of Community Medicine And Public Health, vol. 6, no. 2, Jan. 2019, pp. 454-60, doi:10.18203/2394-6040.ijcmph20185510.