PHOMMANITH , Khamsone, Chalearnsack OUNKEO, Oudom BOUSITH, and Vatsana KEOPHASITH. “A Study Mathematics Achievement by Using Problem-Based Learning for Grade 1 Students”. Souphanouvong University Journal Multidisciplinary Research and Development 7, no. 1 (October 7, 2021): 70–78. Accessed July 25, 2026. https://su-journal.com/index.php/su/article/view/98.