Chanprom, Panprachan, Seree Khum–un, and Ghirana Jirachotdaecho. 2022. “Examining the Ability to Solve Mathematical Problems of First–Year Secondary School Students through Polya’s Problem–Solving Process”. Journal of Humanities and Social Sciences, Rajapruk University 8 (1):327-43. https://so03.tci-thaijo.org/index.php/rpu/article/view/260281.