Gaya APA

Atkinson, H, A, C. (1990). Coal resources in central Sumatra Indonesia . Bandung: Directorate General of Geology and Mineral Resources.

Gaya MLA

Atkinson, Hardjono, And, C.m.. "Coal resources in central Sumatra Indonesia". Bandung: Directorate General of Geology and Mineral Resources, 1990. Text.