Firmansah. PENINGKATAN MOTIVASI BELAJAR SISWA MELALUI BERBASIS PROBLEM BASED LEARNING PADA MATERI PENCEMARAN AIR KELAS X DI SMA NEGERI 1 EMPANG. JBK [Internet]. 2021 Sep. 4 [cited 2025 Mar. 2];3(2):82-5. Available from: https://e-journal.unmas.ac.id/index.php/JBK/article/view/8072