@article{ref1,
title="Prevalence of self-reported physically active adults--United States, 2007",
journal="MMWR: Morbidity and mortality weekly report",
year="2008",
author="Centers for Disease Control and Prevention, USA, ",
volume="57",
number="48",
pages="1297-1300",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0149-2195",
doi="",
url="http://dx.doi.org/"
}