ดาวเรือง ศ. “Application of cause and effect charts to find the cause of service problems of Siam Technique”. Research and Development Journal Sisaket Rajabhat University, vol. 6, no. 1, Oct. 2020, pp. 22-38, https://so01.tci-thaijo.org/index.php/sskru-resarch/article/view/243581.