Não informado. (1976). Essence. York University, Atkinson College, Department of Psychology.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Essence. Ontario, Canada: York University, Atkinson College, Department of Psychology, 1976.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Essence. York University, Atkinson College, Department of Psychology, 1976.
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