Sudirman, Dedy Juliandri Panjaitan. Development of Problem-Based Learning Devices to Improve Mathematics Problem Solving Ability and Learning Independence of Labuhanbatu Private Junior High School Students. IJERE [Internet]. 2023 Sep. 30 [cited 2024 Nov. 1];2(2):384-9. Available from: https://ejournal.ipinternasional.com/index.php/ijere/article/view/553