Gaya APA

Energy, M, O, M, A. (1987). Ombilin Coal Mine Development And Transportation Project Feasibility Study Volume I Executive Summary . Bandung: Pusat Sumber Daya Geologi.

Gaya MLA

Energy, Ministry, Of, Mines, And. "Ombilin Coal Mine Development And Transportation Project Feasibility Study Volume I Executive Summary". Bandung: Pusat Sumber Daya Geologi, 1987. Batubara.