Não informado. (2004). Information Circular. Department of Natural Resources, Division of Geological Survey.
Chicago (17e ed.) BronvermeldingNão informado. Information Circular. Columbus, Ohio: Department of Natural Resources, Division of Geological Survey, 2004.
MLA (8e ed.) BronvermeldingNão informado. Information Circular. Department of Natural Resources, Division of Geological Survey, 2004.
Let op: Deze citaties zijn niet altijd 100% accuraat.