บุญหนุน สิชาภัทร. “Free Online English Dictionaries: Their Optimum Use for English Learning and Teaching”. Journal of Humanities and Social Sciences, Rajapruk University 5, no. supplement (December 31, 2019): 1–14. Accessed April 26, 2024. https://so03.tci-thaijo.org/index.php/rpu/article/view/231785.