Gaya APA

Mangunwidjaya, A, (. (1980). Geological Study of the Caol Reserves and Quality of West Air Laya Area (DG Drilling Series Report) . : Mineral Teknology Development Centre P.N. Tambang Batubara.

Gaya MLA

Mangunwidjaya, Ambyo, (dkk). "Geological Study of the Caol Reserves and Quality of West Air Laya Area (DG Drilling Series Report)". : Mineral Teknology Development Centre P.N. Tambang Batubara, 1980. Text.