Okumura, M. ., and A. . Onthanee. “Effectiveness of Authentic Learning on Japanese Honorific Speaking Skills of Japanese Major Students in Thailand”. Kasetsart Journal of Social Sciences, vol. 43, no. 2, Apr. 2022, pp. 329-36, https://so04.tci-thaijo.org/index.php/kjss/article/view/258491.