@article{ref1,
title="Case definitions in public health",
journal="American journal of public health",
year="1991",
author="Seligman, P. J. and Matte, T. D.",
volume="81",
number="2",
pages="161-162",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0090-0036",
doi="",
url="http://dx.doi.org/"
}