Gaya APA

Johnson, C. et al (1986). North Sumatra Geochemical and Mineral Exploration Project NSGMEP, Mineral Exploration of The Hutabargot-Panyabungan Area, Tapanuli District, Sumatra Utara, Northern Sumatra:A Final Report . Bandung: Pusat Sumber Daya Geologi.

Gaya MLA

Johnson, C.C. et al. "North Sumatra Geochemical and Mineral Exploration Project NSGMEP, Mineral Exploration of The Hutabargot-Panyabungan Area, Tapanuli District, Sumatra Utara, Northern Sumatra:A Final Report". Bandung: Pusat Sumber Daya Geologi, 1986. Geokimia.