Situmorang RS, Hutapea NM, Armis. Development of problem-based learning materials on linear programming to facilitate students’ mathematical problem-solving skills. JA [Internet]. 2024 Aug. 30 [cited 2025 Dec. 17];7(1):1-11. Available from: https://ojs-staging.upp.ac.id/index.php/absis/article/view/2339