@article{ref1,
title="Bicycle sharing in the USA: state of the art",
journal="ITE journal",
year="2012",
author="Kahn, Robert",
volume="82",
number="9",
pages="32-36",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0162-8178",
doi="",
url="http://dx.doi.org/"
}