@article{ref1,
title="How to make color light signals more effective",
journal="Railway system controls",
year="1972",
author="Cox, Jennifer",
volume="3",
number="3",
pages="20-27",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0096-2309",
doi="",
url="http://dx.doi.org/"
}