Gaya APA

Cooperative Research Invesgation Peat Formation, Riau, Sumatera July and August, 1987 Directorate Of Mineral Resources, Indonesia and U.S. Geological Survey. (1987). Bandung: Pusat Sumber Daya Geologi.

Gaya MLA

Cooperative Research Invesgation Peat Formation, Riau, Sumatera July and August, 1987 Directorate Of Mineral Resources, Indonesia and U.S. Geological Survey. . Bandung: Pusat Sumber Daya Geologi, 1987. Batubara.