Chanprom, Panprachan, Nopporn Yamsang, and Woranuch Yamsang. “The Development of Mathematics Learning Activities Using Constructivist Theory on Parallel Lines for Matthayom Sueksa Two Students at Ramkhamhaeng University Demonstration School (Secondary Level)”. Journal of Humanities and Social Sciences, Rajapruk University 10, no. 1 (April 30, 2024): 352–367. accessed December 24, 2025. https://so03.tci-thaijo.org/index.php/rpu/article/view/277495.