@article{ref1,
title="The Playground Survey",
journal="American journal of sociology",
year="1914",
author="Curtis, Henry S.",
volume="19",
number="6",
pages="792-812",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0002-9602",
doi="10.1086/212338",
url="http://dx.doi.org/10.1086/212338"
}