@article{ref1,
title="Physical activity and bone strength",
journal="Scandinavian journal of medicine and science in sports",
year="2004",
author="Schwarz, Peter",
volume="14",
number="1",
pages="1-1",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0905-7188",
doi="",
url="http://dx.doi.org/"
}