@article{ref1,
title="Crowds, riots and the police: An observational study of collective violence",
journal="Aggressive behavior",
year="1993",
author="Adang, Otto M. J.",
volume="19",
number="1",
pages="37-38",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0096-140X",
doi="",
url="http://dx.doi.org/"
}