Gaya APA

Sumartono, . (1984). An Invetigation Of The Belok Gadang Manganese Deposits Natal-North Sumatra ( Indonesia) . London: Departemen of geologi chelsea college (Universitas Of London).

Gaya MLA

Sumartono, . "An Invetigation Of The Belok Gadang Manganese Deposits Natal-North Sumatra ( Indonesia)". London: Departemen of geologi chelsea college (Universitas Of London), 1984. Logam.