@article{ref1,
title="Comparison of operator performance on a tracking task using discretely and continuously variable controls",
journal="Journal of applied psychology",
year="1968",
author="Hammerton, M. and Tickner, A. H.",
volume="52",
number="4",
pages="319-320",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0021-9010",
doi="",
url="http://dx.doi.org/"
}