P. Hutagaol, “Pengaruh Model Pembelajaran Group Investigation Terhadap Hasil Belajar Siswa Pada Materi Pencemaran Lingkungan Di Kelas X SMA Negeri 2 Bandar Tahun Pelajaran 2020/2021: The Influence of the Group Investigation Learning Model on Student Learning Outcomes On Environmental Pollution Materials in Class X SMA Negeri 2 Bandar Academic Year 2020/2021”, JMO, vol. 3, no. 1, pp. 40–45, Apr. 2021.