Basak, S., R. Mukherjee, S. Chowdhury, S. Roy, R. Banerjee, and R. Bhattacharya. “Evaluation of Cardiac Function in COPD Patients and Correlation With Disease Severity: A Cross Sectional Study”. Asian Journal of Medical Sciences, vol. 12, no. 3, Mar. 2021, pp. 14-19, doi:10.3126/ajms.v12i3.32606.