Gaya APA

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

Gaya MLA

Young, R.D. "Integrated Geological Survey or Northern Sumatra Directorate Of Mineral Resources May 1980". Bandung: Pusat Sumber Daya Geologi, 1980. Encyclopaedia.