Külpe, O., Pillsbury, W. B., & Titchener, E. B. (1901). Introduction to philosophy: A handbook for students of psychology, logic, ethics, æsthetics and general philosophy. S. Sonnenschein & co., limited; The Macmillan Co..
Lua i Stíl Chicago (17ú heag.)Külpe, Oswald, W. B. Pillsbury, agus Edward Bradford Titchener. Introduction to Philosophy: A Handbook for Students of Psychology, Logic, Ethics, æsthetics and General Philosophy. London, New York: S. Sonnenschein & co., limited; The Macmillan Co., 1901.
Lua MLA (8ú heag.)Külpe, Oswald, et al. Introduction to Philosophy: A Handbook for Students of Psychology, Logic, Ethics, æsthetics and General Philosophy. S. Sonnenschein & co., limited; The Macmillan Co., 1901.
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