SIMBOLON, P. .; SIMBOLON, N. . Learning Environment with the Learning Concentration on Students. Proceeding International Conference on Religion, Science and Education, [S. l.], v. 1, p. 109–115, 2022. Disponível em: https://sunankalijaga.org/prosiding/index.php/icrse/article/view/781. Acesso em: 19 apr. 2026.