Gaya APA
Limited, M, E, C. (1982).
Republic of indonesia directorate general of mines .
Bandung:
Pusat Sumber Daya Geologi.
Gaya MLA
Limited, Montreal, Engineering, Company,.
"Republic of indonesia directorate general of mines".
Bandung:
Pusat Sumber Daya Geologi,
1982.
Batubara.