@article{ref1,
title="Heart rate and oxygen consumption during active psychological challenge: the effects of level of difficulty",
journal="Psychophysiology",
year="1986",
author="Carroll, D. and Turner, J. R. and Hellawell, J. C.",
volume="23",
number="2",
pages="174-181",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0048-5772",
doi="",
url="http://dx.doi.org/"
}