Abdul Ghani Waseem, Kaleem Ullah Toori, Mohammad Iqbal, Asim Zulfiqar, Sharif-uz-Zaman. (2009). Effect of Job Environment on Pulmonary Functions of Railway Employees. Journal of Rawalpindi Medical College, 12(2). Retrieved from https://journalrmc.com/index.php/JRMC/article/view/753