Gaya APA
JR, H, T. (1952).
MINING PRACTICE AT THE UMBILIN COAL MINE WEST-CENTRAL SUMATRA MEMORANDUNG .
Bandung:
Direktorat Batubara.
Gaya MLA
JR, HENRY, TARRING,.
"MINING PRACTICE AT THE UMBILIN COAL MINE WEST-CENTRAL SUMATRA MEMORANDUNG".
Bandung:
Direktorat Batubara,
1952.
Batubara.