Não informado. (2004). Information Circular. Department of Natural Resources, Division of Geological Survey.
Chicago-viite (17. p.)Não informado. Information Circular. Columbus, Ohio: Department of Natural Resources, Division of Geological Survey, 2004.
MLA-viite (8. p.)Não informado. Information Circular. Department of Natural Resources, Division of Geological Survey, 2004.
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