Manuy, N., and C. Laohawiriyanon. “Effects of Using Captioned and Keyword-Only Pictures on Grade 2 Learners’ English Speaking Ability”. Journal of International Studies, Prince of Songkla University, vol. 6, no. 2, Mar. 2018, pp. 227-48, https://so03.tci-thaijo.org/index.php/jis/article/view/114529.