Chomjumjung, Kantana, and Phornchai Phardthaisong. 2022. “The Development of Problem Solving Ability in Mathematics of Muthayomsuksa 3 Students by Using Open Approach”. Journal of Roi Et Rajabhat University 16 (1):106-16. https://so03.tci-thaijo.org/index.php/reru/article/view/246601.