@article{ref1,
title="Longevity of endurance skiers",
journal="Medicine and science in sports",
year="1974",
author="Karvonen, M. J. and Klemola, H. and Virkajärvi, J. and Kekkonen, A.",
volume="6",
number="1",
pages="49-51",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0025-7990",
doi="",
url="http://dx.doi.org/"
}