@article{ref1,
title="Measurement of reciprocity and unidirectionality in social behavior illustrated with examples from chimpanzee research",
journal="Aggressive behavior",
year="1989",
author="Hemelrijk, CK",
volume="15",
number="1",
pages="62-63",
abstract="<p>[Abstract unavailable]</p>",
language="en",
issn="0096-140X",
doi="",
url="http://dx.doi.org/"
}