Ahasan, HAM Nazmul, and Homayra Tahseen Hossain. “COPD Guidelines: Old Gold Versus New Gold”. Bangladesh Journal of Medicine 29, no. 1 (February 8, 2018): 31–35. Accessed April 26, 2024. https://www.banglajol.info/index.php/BJMED/article/view/35405.