Subarudi, S., H. Kartodihardjo, S. Soedomo, H. Sapardi, and M. Z. Muttaqin. “Analysing Policy Formulation for Coal Mining Activities Within State Forest Zone in Indonesia: A Case Study of East Kalimantan Province”. International Journal of Sciences: Basic and Applied Research (IJSBAR), vol. 26, no. 1, Apr. 2016, pp. 314-30, https://gssrr.org/index.php/JournalOfBasicAndApplied/article/view/5425.