Muller, P. O., Hames, E. M., & De Blij, H. J. (1997). Study guide, de Blij and Muller's 'Geography: Realms, regions and concepts' (8th ed.). Wiley.
Lua i Stíl Chicago (17ú heag.)Muller, Peter O., Elizabeth Muller Hames, agus Harm J. De Blij. Study Guide, De Blij and Muller's 'Geography: Realms, Regions and Concepts'. 8th ed. New York ; Chichester: Wiley, 1997.
Lua MLA (8ú heag.)Muller, Peter O., et al. Study Guide, De Blij and Muller's 'Geography: Realms, Regions and Concepts'. 8th ed. Wiley, 1997.
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