Ghea Setyarini, Aditya Permana, and Rizki Fuji Handika. “Literature Review: Application of Problem Based Learning Model to Improving Problem Solving Ability and Student Mathematics Learning Outcomes in Elementary School”. International Conference on Elementary Education, Vol. 5, no. 1, June 2023, pp. 260-73, http://proceedings2.upi.edu/index.php/icee/article/view/3118.