@article{ref1,
title="Analysis of detection and service systems on freeways",
journal="Accident analysis and prevention",
year="1971",
author="Keller, H.",
volume="3",
number="3",
pages="149-192",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0001-4575",
doi="",
url="http://dx.doi.org/"
}