Ullah, Rehman, Najeeb Ul Haq, Nauman Iqbal, Najam Masood, and Ali Yar Khan. 2025. “Association of Baseline Serum Vitamins A and C With Disease Severity in COVID-19 Patients”. Pakistan Journal of Chest Medicine 31 (2):93-100. http://www.pjcm.net/index.php/pjcm/article/view/1034.