@article{ref1,
title="The City: Suggestions for the Investigation of Human Behavior in the City Environment",
journal="American journal of sociology",
year="1915",
author="Park, Robert E.",
volume="20",
number="5",
pages="577-612",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0002-9602",
doi="10.1086/212433",
url="http://dx.doi.org/10.1086/212433"
}