Yuliandra, Berry, Agus Sutanto, and Hendris Prasojo. “An Assessment Framework for Small-Scale Coal Mining Based on Lean Thinking and Green Mining Concept”. International Series on Interdisciplinary Science and Technology 3, no. 2 (October 20, 2018): 170–175. Accessed July 14, 2025. http://insist.unila.ac.id/index.php/ojs/article/view/114.