Piryani, R. M., and S. Piryani. “COPD in Non-Smokers in South Asia: An Under Estimated and Unrecognized Condition”. Journal of Liaquat University of Medical & Health Sciences, vol. 22, no. 03, Oct. 2023, p. 154, http://121.52.154.205/index.php/jlumhs/article/view/1259.