Lewis, D. J. (1963). Scientific principles of psychology. Prentice - hall.
Lua i Stíl Chicago (17ú heag.)Lewis, Donald J. Scientific Principles of Psychology. New Jersey: Prentice - hall, 1963.
Lua MLA (9ú heag.)Lewis, Donald J. Scientific Principles of Psychology. Prentice - hall, 1963.
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