Birdsall, S. S. (1992). Outline of American geography: Regional landscapes of the united States (4th ed.). John Willey.
Citace podle Chicago (17th ed.)Birdsall, Stephen S. Outline of American Geography: Regional Landscapes of the United States. 4th ed. California: John Willey, 1992.
Citace podle MLA (9th ed.)Birdsall, Stephen S. Outline of American Geography: Regional Landscapes of the United States. 4th ed. John Willey, 1992.
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