Semple, E. C., & Ratzel, F. (1911). Influences of geographic environment, on the basis of Ratzel's system of anthropo-geography. H. Holt and Co..
Lua i Stíl Chicago (17ú heag.)Semple, Ellen Churchill, agus Friedrich Ratzel. Influences of Geographic Environment, on the Basis of Ratzel's System of Anthropo-geography. New York: H. Holt and Co., 1911.
Lua MLA (8ú heag.)Semple, Ellen Churchill, agus Friedrich Ratzel. Influences of Geographic Environment, on the Basis of Ratzel's System of Anthropo-geography. H. Holt and Co., 1911.
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