@article{ref1,
title="How does the child know? Origins of the symbol in the theories of Piaget and Werner",
journal="Journal of the American Academy of Psychoanalysis",
year="1980",
author="Barten, S. S.",
volume="8",
number="1",
pages="77-94",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0090-3604",
doi="",
url="http://dx.doi.org/"
}