@article{ref1,
title="Mortality among U.S. underground coal miners: A 23‐year follow‐up",
journal="American journal of industrial medicine",
year="2008",
author="Attfield, M. D. and Kuempel, E. D.",
volume="51",
number="4",
pages="231-245",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0271-3586",
doi="10.1002/ajim.20560",
url="http://dx.doi.org/10.1002/ajim.20560"
}