Sumiatiningsih, and Nur Efendi. “The Student Problem Solving Skills in Science Subjects Based on Class Rankings ”. Academia Open 50 (August 23, 2021): 10.21070/acopen.5.2021.2240. Accessed May 3, 2024. https://acopen.umsida.ac.id/index.php/acopen/article/view/2240.