Nem, S., D. Inprasitha, and D. Changsri. “First Grade Student’s Mathematical Representation in the Classroom Using Lesson Study and Open Approach”. KKU Research Journal (Graduate Studies) Humanities and Social Sciences, vol. 10, no. 2, Apr. 2023, pp. 98-112, https://so04.tci-thaijo.org/index.php/gskkuhs/article/view/252813.