Boonchom, W., and J. . Tipparach. “A Study of Effectiveness on the 6 Principles for Exemplary Teaching of English Learners”. Journal of Graduate School, Pitchayatat, Ubon Ratchathani Rajabhat University, vol. 16, no. 2, Aug. 2021, pp. 241-53, https://so02.tci-thaijo.org/index.php/Pitchayatat/article/view/249668.