@article{ref1,
title="Cluster investigation--the importance of counting everyone",
journal="Journal of public health medicine",
year="2003",
author="Gavin, Anna T.",
volume="25",
number="3",
pages="262-262",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0957-4832",
doi="",
url="http://dx.doi.org/"
}