ดาวเรือง ศ. . . “Application of Cause and Effect Charts to Find the Cause of Service Problems of Siam Technique”. SSKRU Research and Development Journal, vol. 6, no. 1, Oct. 2020, pp. 22-38, https://so01.tci-thaijo.org/index.php/sskru-resarch/article/view/243581.