(Rapeepat Kaewam) ระพีพัฒน์ แก้วอ่ำ. 2018. “DEVELOPING OF LEARNING ACTIVITIES FOCUSING ON MATHEMATICAL CONNECTION USE PROBLEM-BASED LEARNING FOR GRADE 9 STUDENTS”. Journal of Education and Innovation 19 (4):214-22. https://so06.tci-thaijo.org/index.php/edujournal_nu/article/view/108456.