@article{ref1,
title="Classification of sports",
journal="Journal of the American College of Cardiology",
year="1994",
author="Mitchell, J. H. and Haskell, William L. and Raven, P. B.",
volume="24",
number="4",
pages="864-866",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0735-1097",
doi="",
url="http://dx.doi.org/"
}