Chaudhari, R., and L. Shrimali. “Study of Clinical, Electrocardiographic and Echocardiographic Profile in Patients With Chronic Obstructive Pulmonary Disease”. International Journal of Research in Medical Sciences, vol. 6, no. 5, Apr. 2018, pp. 1716-20, doi:10.18203/2320-6012.ijrms20181765.