@article{ref1,
title="On the length-difficulty relation in skill performance",
journal="Journal of experimental psychology",
year="1967",
author="Swink, J. and Trumbo, D. and Noble, M.",
volume="74",
number="3",
pages="356-362",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0022-1015",
doi="",
url="http://dx.doi.org/"
}