@article{ref1,
title="Number of alternatives and sequence length in acquisition of a step-function tracking task",
journal="Perceptual and motor skills",
year="1965",
author="Trumbo, D. and Noble, M. and Ulrich, L.",
volume="21",
number="2",
pages="563-569",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0031-5125",
doi="",
url="http://dx.doi.org/"
}