@article{ref1,
title="Visibility of exit signs in clear and smoky conditions",
journal="Fire technology",
year="1993",
author="Collins, B. L. and Dahir, M. S. and Madrzykowski, D.",
volume="29",
number="2",
pages="154-182",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0015-2684",
doi="10.1007/BF01038537",
url="http://dx.doi.org/10.1007/BF01038537"
}