Hutasoit, Imelda. “Developing an Instructional Package of Environmental Education (EnMor Book) Based On Ecology In Improving Student’s Environmental Moral Behavior”. IJEEM - Indonesian Journal of Environmental Education and Management 2, no. 1 (January 31, 2017): 38–43. Accessed November 24, 2024. https://journal.unj.ac.id/unj/index.php/ijeem/article/view/3709.