Freeman, O. W. (1945). Physiographic divisions of the Columbia intermontane province. [n.p..
Cita Chicago Style (17a ed.)Freeman, Otis W. Physiographic Divisions of the Columbia Intermontane Province. [n.p., 1945.
Cita MLA (8a ed.)Freeman, Otis W. Physiographic Divisions of the Columbia Intermontane Province. [n.p., 1945.
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