Clifford, N. J., & Valentine, G. (2010). Key methods in geography (2nd ed.). Sage.
Lua i Stíl Chicago (17ú heag.)Clifford, Nicholas J., agus Gill Valentine. Key Methods in Geography. 2nd ed. Thousand Oaks, CA: Sage, 2010.
Lua MLA (9ú heag.)Clifford, Nicholas J., agus Gill Valentine. Key Methods in Geography. 2nd ed. Sage, 2010.
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