Krongchon N ,Piboon K ,Oppawongsapat D. “Effectiveness of Tai Chi Exercise Program on Self-Efficacy, Exercise Behavior and Pulmonary Function Among COPD Patients”. Journal of The Department of Medical Services, vol. 42, no. 4, Aug. 2017, pp. 89-98, https://he02.tci-thaijo.org/index.php/JDMS/article/view/248845.