Apiworathanakorn, Yongyuth, Art-Ong Jumsai Na Ayudhya, Rachanont Supapongpichate, and Sayam Aroonsrimorakot. 2019. “A Model of Competency Development for Internal Environmental Auditors in IS014001-Certified Organizations”. Kasetsart Journal of Social Sciences 40 (1):129-35. https://so04.tci-thaijo.org/index.php/kjss/article/view/239821.