Gaya APA
Geologi, P, S, D. (1999).
Proyek integrated Study For Coal Development In Central Part Of Sumatera' CTA-231 .
Bandung:
Pusat Sumber Daya Geologi.
Gaya MLA
Geologi, Pusat, Sumber, Daya.
"Proyek integrated Study For Coal Development In Central Part Of Sumatera' CTA-231".
Bandung:
Pusat Sumber Daya Geologi,
1999.
Batubara.