Walker, E. L. (1970). Psychology as a natural and social science. Brooks/Cole.
Lua i Stíl Chicago (17ú heag.)Walker, Edward L. Psychology as a Natural and Social Science. Belmont, Calif: Brooks/Cole, 1970.
Lua MLA (9ú heag.)Walker, Edward L. Psychology as a Natural and Social Science. Brooks/Cole, 1970.
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