Sari DK, Akhsan H. Development of project-based student worksheets on renewable energy by utilising rubber fruit shell waste to increase motivation. Sriwij. University Learn. and Edu. Int. j [Internet]. 2025 May 12 [cited 2025 Jun. 5];1(3):139-52. Available from: https://sule-ij.ejournal.unsri.ac.id/index.php/sule-ij/article/view/15