Loakhajorn, Kolawatch, Thirapat Assawachaiporn, and Pichakorn Khowasinth. 2022. “Cigarette Smoking: A Major Cause of Emphysema”. International Journal of Formal Sciences: Current and Future Research Trends 15 (1):112-22. https://ijfscfrtjournal.isrra.org/index.php/Formal_Sciences_Journal/article/view/730.