Sofia Shoukat, Maheen Saad, Muhammad Razaq, Nadia Qazi, Jahangir Zaib and Tahira Jehangir 2022. Role of pneumococcal and influenza vaccine in prevention and vitamin E with beta carotene in treatment of pneumonia in patients with COPD. Pakistan Journal of Chest Medicine. 28, 1 (Mar. 2022), 13–19.