Petch-in, S., C. Lumduanhom, K. Piasai, A. Janjaroon, S. Hajisalah, and W. Pho-on. “A STUDY OF MATHAYOMSUKSA I STUDENTS’ LEARNING OUTCOME ON COMBINATORICS VIA CONSTRUCTIVIST TEACHING”. Journal of Industrial Education, vol. 18, no. 2, Aug. 2019, pp. 101-9, https://ph01.tci-thaijo.org/index.php/JIE/article/view/190279.