ภมรพล ศ., and นุ่มพูล จ. “Factors Predicting Constipation in Critically Ill Patients”. The Journal of Thailand Nursing and Midwifery Council, vol. 34, no. 1, Feb. 2019, pp. 88-103, https://he02.tci-thaijo.org/index.php/TJONC/article/view/152511.