Gaya APA
Hartoyo, B., Saleh, R. (1994).
Some Informations Of Coal Mining Investment In Indonesia .
Bandung:
Pusat Sumber Daya Geologi.
Gaya MLA
Hartoyo, Bambang., Saleh, Rachmat.
"Some Informations Of Coal Mining Investment In Indonesia".
Bandung:
Pusat Sumber Daya Geologi,
1994.
Batubara.