Gaya APA

v.falkie, T., V.e.mckelvey, . (1976). Coal Resource Classification System Of The U.S.Berseau Of Mines And U.S.Geological Survey . Bandung: Geological Survey Bulletin.

Gaya MLA

v.falkie, Thomas., V.e.mckelvey, . "Coal Resource Classification System Of The U.S.Berseau Of Mines And U.S.Geological Survey". Bandung: Geological Survey Bulletin, 1976. Batubara.