@article{ref1,
title="From egocentric to cooperative play in young children. A normative study",
journal="Journal of the American Academy of Child Psychiatry",
year="1976",
author="Whiteside, M. F. and Büsch, F. and Horner, T.",
volume="15",
number="2",
pages="294-313",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0002-7138",
doi="",
url="http://dx.doi.org/"
}