@article{ref1,
title="Play--a pedagogic necessity for children",
journal="Kinderkrankenschwester",
year="1990",
author="Heuss, G. E.",
volume="9",
number="4",
pages="112-113",
abstract="<p>[Abstract unavailable]</p><p>Language: de</p>",
language="de",
issn="0723-2276",
doi="",
url="http://dx.doi.org/"
}