@article{ref1,
title="Sinus arrhythmia as a measure of mental load",
journal="Ergonomics",
year="1974",
author="Boyce, P. R.",
volume="17",
number="2",
pages="177-183",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0014-0139",
doi="10.1080/00140137408931336",
url="http://dx.doi.org/10.1080/00140137408931336"
}