Sochaiyan, C., Phattarachaleeku ม., & Chutiman, N. (2022). Development of Mathematical Problem Solving Skills Using Problem-Based Learning with Digital Media on Ratio, Proportion and Percentage for Mathayomsuksa 1 Students. Journal of Education Rajabhat Maha Sarakham University, 19(3), 201–214. retrieved from https://so06.tci-thaijo.org/index.php/edu-rmu/article/view/261148