Isaacs, N. (1960). New light on children's ideas of number: The work of professor Piaget. Ward Lock Educational.
Παραπομπή σε μορφή Chicago (17η εκδ.)Isaacs, Nathan. New Light on Children's Ideas of Number: The Work of Professor Piaget. London: Ward Lock Educational, 1960.
Παραπομπή σε μορφή MLA (8th εκδ.)Isaacs, Nathan. New Light on Children's Ideas of Number: The Work of Professor Piaget. Ward Lock Educational, 1960.
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