Khumkongsuwan, K. ., S. . Hajisalah, A. . . Janjaroon, and A. . Watthanawisut. “A STUDY OF MATTHAYOMSUKSA II STUDENTS’ PROOF ABILITIES IN PARALLEL-LINES TOPICS VIA THE CONSTRUCTIVIST LEARNING MODEL (CLM)”. Journal of Industrial Education, vol. 19, no. 2, Sept. 2020, pp. 50-59, https://ph01.tci-thaijo.org/index.php/JIE/article/view/240523.