@article{ref1,
title="Threshold limit values for carbon monoxide",
journal="Archives of environmental health",
year="1970",
author="Grut, A. and Astrup, P. and Challen, P. J. and Gerhardsson, G.",
volume="21",
number="4",
pages="542-544",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0003-9896",
doi="",
url="http://dx.doi.org/"
}