@article{ref1,
title="Spectral analysis of sinus arrhythmia: a measure of mental effort",
journal="Human factors",
year="1987",
author="Vicente, K. J. and Thornton, D. C. and Moray, N.",
volume="29",
number="2",
pages="171-182",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0018-7208",
doi="",
url="http://dx.doi.org/"
}