ANALISIS HUBUNGAN NILAI HGI (HARDGROVE GRINDABILITY INDEX) ASH CONTENT INHERENT MOISTURE DAN TOTAL SULFUR TERHADAP NILAI KALORI BATUBARA DI PT. GEOSERVICES SAMARINDA KALIMANTAN TIMUR. GEOSAINS KUTAI BASIN, [S. l.], v. 5, n. 1, p. 31–37, 2022. DOI: 10.30872/geofisunmul.v5i1.789. Disponível em: https://jurnal.fmipa.unmul.ac.id/index.php/geofis/article/view/789. Acesso em: 8 sep. 2025.