@article{ref1,
title="Different speed limits for cars and trucks: Do they affect vehicle speeds?",
journal="Journal of safety research",
year="1991",
author="Esterlitz, Joy R. and Zador, Paul L. and Baum, H. M. and Penny, M.",
volume="22",
number="2",
pages="117-117",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0022-4375",
doi="",
url="http://dx.doi.org/"
}