Julma, Kattaleya, and Metta Marwiang. 2019. “The Effectiveness of Multimedia Instructional Material on at Risk Student’s Achievement in Mathematics”. Journal of Education Khon Kaen University (Graduate Studies Research) 13 (3-4):1-8. https://so02.tci-thaijo.org/index.php/EDGKKUJ/article/view/242943.