คำแก่น พ., ชัยอาจ จ., and ภิญโญคำ น. “Factors Predicting Symptom Clusters Among Persons With Chronic Obstructive Pulmonary Disease”. Nursing Journal CMU, vol. 46, no. 2, June 2019, pp. 24-35, https://he02.tci-thaijo.org/index.php/cmunursing/article/view/197079.