Kalyan, M., S. A. Kanitkar, A. Gupta, D. Sharma, and S. Singh. “Effect of Passive Smoking As a Risk Factor for Chronic Obstructive Pulmonary Disease in Normal Healthy Women”. International Journal of Research in Medical Sciences, vol. 4, no. 11, Dec. 2016, pp. 4970-3, doi:10.18203/2320-6012.ijrms20163800.