Krishna Appaji, C. Sri, and P. Ravinder. “A Correlation Between Severity of Chronic Obstructive Pulmonary Disorders, Electrocardiography and Echocardiography of Patients: A Prospective Observational Study”. International Journal of Advances in Medicine 7, no. 12 (November 23, 2020): 1777–1780. Accessed October 31, 2025. https://www.ijmedicine.com/index.php/ijam/article/view/2599.