Pimthong, P., S. Soparat, and S. Chamrat. “The Constructionist Paradigm Shift of Teachers in 21th Century Learning”. Kasetsart Journal of Social Sciences, vol. 38, no. 1, Apr. 2017, pp. 470-81, https://so04.tci-thaijo.org/index.php/kjss/article/view/242645.