Gupta, Rajiv, and Sfurti Mann. 2018. “Correlation Between COPD And Echocardiographic Features With Severity Of Disease: Correlation Between COPD And Echocardiographic Features With Severity Of Disease”. National Journal of Integrated Research in Medicine 7 (1):26-30. http://nicpd.ac.in/ojs-/index.php/njirm/article/view/1038.