Não informado. (1972). Geographical survey. Ball State University, Department of Geography and Geology.
Chicago-referens (17:e uppl.)Não informado. Geographical Survey. Muncie, Ind: Ball State University, Department of Geography and Geology, 1972.
MLA-referens (8:e uppl.)Não informado. Geographical Survey. Ball State University, Department of Geography and Geology, 1972.
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