Y. Apiworathanakorn, A.-O. Jumsai Na Ayudhya, R. Supapongpichate, and S. Aroonsrimorakot, “A model of competency development for internal environmental auditors in IS014001-certified organizations”, kasetsart J. Soc. Sci., vol. 40, no. 1, pp. 129–135, Apr. 2019.