@article{ref1,
title="Agonistic versus amicable targets of attack and defense: consequences for the origin, function, and descriptive classification of play-fighting",
journal="Aggressive behavior",
year="1988",
author="Pellis, SM",
volume="14",
number="2",
pages="85-104",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0096-140X",
doi="",
url="http://dx.doi.org/"
}