@article{ref1,
title="When to retire after concussion?",
journal="British journal of sports medicine",
year="2001",
author="McCrory, P.",
volume="35",
number="6",
pages="380-382",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0306-3674",
doi="",
url="http://dx.doi.org/"
}