Ubaid Ullah Sami, Saeed Ur Rehman, Adnan Ghafoor, Zayed Naser, Saleh Ahmad, Hafeez Ud Din. “Serum Vitamin D Level in Chronic Obstructive Pulmonary Disease and Its Relation With Severity”. Pakistan Journal of Medical & Health Sciences 16, no. 09 (November 28, 2022): 941. Accessed December 22, 2024. https://pjmhsonline.com/index.php/pjmhs/article/view/3030.