@article{ref1,
title="How many resources and how to identify them? Commentary on Boles et al. and Vidulich and Tsang",
journal="Human factors",
year="2007",
author="Wickens, Christopher D.",
volume="49",
number="1",
pages="53-56",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0018-7208",
doi="",
url="http://dx.doi.org/"
}