Walker, R. L. Urban sub-areas as sampling frameworks: A further development. Town Planning Review.
Lua i Stíl Chicago (17ú heag.)Walker, Robert L. "Urban Sub-areas as Sampling Frameworks: A Further Development." Town Planning Review .
Lua MLA (9ú heag.)Walker, Robert L. "Urban Sub-areas as Sampling Frameworks: A Further Development." Town Planning Review, .
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