@article{ref1,
title="Causal chain approaches to the evaluation of highway safety countermeasures",
journal="Journal of safety research",
year="1971",
author="Hall, William K. and O'Day, Joanne",
volume="3",
number="1",
pages="9-20",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0022-4375",
doi="",
url="http://dx.doi.org/"
}