Gaya APA
Lehmann, D, F. (1959).
Report On The State Of The Coal Mines In The Mahakam District .
Bandung:
Pusat Sumber Daya Geologi.
Gaya MLA
Lehmann, Dipl.-Berging., F..
"Report On The State Of The Coal Mines In The Mahakam District".
Bandung:
Pusat Sumber Daya Geologi,
1959.
Batubara.