Kittipalo, Phrama Kwanchai, and Kriangsak Ploysaeng. “Principles and Art of Speaking”. Mahachula Academic Journal 5, no. ฉบับพิเศษ (August 20, 2018): 40–51. Accessed May 1, 2024. https://so04.tci-thaijo.org/index.php/JMA/article/view/141269.