Gaya APA

Johari, S., Young, R. (1980). Integrated Geological Survey Of Northern Sumatra Directorate Of Mineral Resources May 1980 . Bandung: Pusat Sumber Daya Geologi.

Gaya MLA

Johari, S.., Young, R.D.. "Integrated Geological Survey Of Northern Sumatra Directorate Of Mineral Resources May 1980". Bandung: Pusat Sumber Daya Geologi, 1980. Bukan Logam.