@article{ref1,
title="The detectability of two slow vehicle warning devices",
journal="Journal of safety research",
year="1972",
author="Asper, O",
volume="4",
number="2",
pages="85-89",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0022-4375",
doi="",
url="http://dx.doi.org/"
}