@article{ref1,
title="Visual contrast sensitivity functions obtained with colored and achromatic gratings",
journal="Human factors",
year="1979",
author="Nelson, M. A. and Halberg, R. L.",
volume="21",
number="2",
pages="225-228",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0018-7208",
doi="",
url="http://dx.doi.org/"
}