Wongwan, Pasutha, Simmee Oupra, and Somlak Liangprayoon. 2019. “Development of English Speaking Ability Baedsed on Communicative Language Teaching (CLT): Case Study in a Language Center”. Chophayom Journal 30 (3):73-82. https://so01.tci-thaijo.org/index.php/ejChophayom/article/view/216612.