Pratama, Reziono. “Development of Mathematics Learning Devices Through Problem Based Learning Models to Improve Problem Solving Mathematics Ability Students SMP Swasta Salsa”. Advances in Social Sciences Research Journal 5, no. 10 (November 5, 2018). Accessed November 22, 2024. https://journals.scholarpublishing.org/index.php/ASSRJ/article/view/5392.