Saima Shaheen, Maria Sarfraz, Anum Saeedullah, Nadia Qazi, Tahira Jehangir and Sara Mariyum (2022) “Role of Supplementation of Vitamin C and D in their Low Serum Values in Critically Ill COPD Patients of Tertiary Care Hospital”, Pakistan Journal of Chest Medicine, 28(1), pp. 46–53. Available at: https://www.pjcm.net/index.php/pjcm/article/view/851 (Accessed: 15December2025).