Thanakoolkaweepong, T., Y. Kongthip, S. Hajisalah, and A. Janjaroon. “The Development of Instructional Geometry Problems Activities to Enhance Critical Problem Solving by Design Thinking Process for Secondary Students”. Journal of Multidisciplinary in Humanities and Social Sciences, vol. 6, no. 2, Apr. 2023, pp. 811-30, https://so04.tci-thaijo.org/index.php/jmhs1_s/article/view/263181.