Agsonsue, P. ., and . E. . Kositpimanvach. “Sustainable Leadership of Private School Principals under Jurisdiction of Khonkaen Educational Office”. Journal of Graduate MCU KhonKaen Campus, vol. 6, no. 3, Sept. 2019, pp. 634-4, https://so02.tci-thaijo.org/index.php/jg-mcukk/article/view/215472.