OPTICAL PROPERTIES OF SOME TERTIARY COALS FROM KUTAI BASIN INDONESIA THEIR DEPOSITIONAL ENVIRONMENTS AND HYDROCARBON POTENTIAL. j.geologi.pertamb. [Internet]. 9 Desember 2016 [dikutip 25 Agustus 2025];2(20). Tersedia pada: https://ejurnal.unikarta.ac.id/index.php/jgp/article/view/206