Budiharto, B. (2021) “Peningkatan Hasil Belajar IPS Melalui Model Pembelajaran Problem Based Learning (PBL) pada Siswa Kelas VIII-A SMP Negeri 1 Ajung”, Education Journal : Journal Educational Research and Development, 5(1), pp. 97–110. doi: 10.31537/ej.v5i1.424.