Srirat, C., S. Hanucharurnkul, S. Aree-Ue, C. Viwatwongkasem, and T. Junda. “Symptom Distress, Cluster, and Management in Thais With COPD”. Pacific Rim International Journal of Nursing Research, vol. 18, no. 3, July 2014, pp. 244-62, https://he02.tci-thaijo.org/index.php/PRIJNR/article/view/17413.