Shannak, Q. A. ., T. M. Najim, and D. I. Madab. “Evaluation of the Level of Vitamin D3 in the Blood Serum of Patients Infected With COVID-19 in Al-Amiriya City”. Technium BioChemMed, vol. 3, no. 2, Aug. 2022, pp. 127-35, doi:10.47577/biochemmed.v3i2.7179.