@article{ref1,
title="Congestion charging and the walking classes",
journal="British medical journal: BMJ",
year="2003",
author="Roberts, Ian",
volume="326",
number="7385",
pages="345-346",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0959-8138",
doi="",
url="http://dx.doi.org/"
}