Gaya APA
W.LUETTING, W. (1985).
Seminar Economic Geologi Of Coal Deposits (including exploration methods) .
Bandung:
Pusat Sumber Daya Geologi.
Gaya MLA
W.LUETTING, WERD.
"Seminar Economic Geologi Of Coal Deposits (including exploration methods)".
Bandung:
Pusat Sumber Daya Geologi,
1985.
Batubara.