Nakthong M, Kaewurai W. A DEVELOPMENT OF PROBLEM-BASED LEARNING ACTIVITY ON THE TOPIC OF ENVIRONMENT AND NATURAL RESOURCE TO ENCOURAGE ABILITY REFLECTIVE THINKING FOR MATTAYOMSUKSA 3 STUDENTS. JBER [Internet]. 2022 Apr. 30 [cited 2024 May 5];8(1):301-12. Available from: https://so06.tci-thaijo.org/index.php/jber/article/view/256982