Khaled El Sayed Foad El Hadidy , Khadiga Mohamed Abougabal , Nilly Helmy Abd Allah , Ahmed Mahmoud Khallaf , Khaled Ahmed Zakaria , Tran., “Prevalence of Abnormal Serum 25-HydroxyVitamin D and Its Association with Hemoglobin Level in Pre-Dialysis Chronic Kidney Disease (CKD) Patients”, CDF, vol. 54, no. 3, pp. 4144–4153, Feb. 2025, doi: 10.48047/w2ap2g70.