@article{ref1,
title="Objective measurement of mental load",
journal="Acta psychologica",
year="1967",
author="Kalsbeek, J. W. and Sykes, R. N.",
volume="27",
number="",
pages="253-261",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0001-6918",
doi="",
url="http://dx.doi.org/"
}