“Correlation of Hospital Anxiety and Depression Scale (HADS) and Six Minute Walk Test (6MWT) Performance in Chronic Obstructive Pulmonary Disease (COPD) Patients”. International Journal of Biomedical Research 11, no. 6 (August 30, 2020): e5419. Accessed March 13, 2025. https://ssjournals.co.in/index.php/ijbr/article/view/5419.