@article{ref1,
title="On the frequency of accidents of different types",
journal="Accident analysis and prevention",
year="1971",
author="Gustavsson, J.",
volume="3",
number="2",
pages="95-112",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0001-4575",
doi="",
url="http://dx.doi.org/"
}