@article{ref1,
title="Operator effort and the measurement of heart-rate variability",
journal="Human factors",
year="1987",
author="Aasman, Jans and Mulder, G. and Mulder, L. J.",
volume="29",
number="2",
pages="161-170",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0018-7208",
doi="",
url="http://dx.doi.org/"
}