Nasruddin, Nasruddin. “Spatial Characteristic of Coal Mining in Kutai Kartarnegara Regency, East Kalimantan Province”. Sumatra Journal of Disaster, Geography and Geography Education 1, no. 2 (December 12, 2017): 152–154. Accessed October 27, 2026. http://sjdgge.ppj.unp.ac.id/index.php/Sjdgge/article/view/101.