APA-čujuhus (7. p.)
Beard, R. M. (1980). An outline of Piaget's developmental psychology. Routledge.
Chicago-čujuhus (17. p.)
Beard, Ruth M. An Outline of Piaget's Developmental Psychology. London: Routledge, 1980.
MLA-čujuhus (9. p.)
Beard, Ruth M. An Outline of Piaget's Developmental Psychology. Routledge, 1980.
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