“The Effect of Harmonica Exercise on Inspiratory Capacity, Dyspnea, Exercise Capacity and Quality of Life of Chronic Obstructive Pulmonary Disease Patients”. Jurnal Respirologi Indonesia 39, no. 1 (January 2, 2020): 1–13. Accessed August 19, 2025. http://www.jurnalrespirologi.org/index.php/jri/article/view/42.