@article{ref1,
title="Assessment of physical activity in population surveys",
journal="Sozial und Praventivmedizin",
year="2001",
author="Rickenbach, M. and Wietlisbach, V.",
volume="46",
number="6",
pages="354-354",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0303-8408",
doi="",
url="http://dx.doi.org/"
}