Thankham, S., Boontongtherng, P., & Jansila, A. (2020). Development of Curriculum Enhancing Mathematical Thinking Skills of Problem Solving for 6th Grade Students. Journal of Education Rajabhat Maha Sarakham University, 17(1), 59–72. Retrieved from https://so06.tci-thaijo.org/index.php/edu-rmu/article/view/251932