@article{ref1,
title="Brightness difference in seeing",
journal="American journal of optometry and archives of American Academy of Optometry",
year="1954",
author="Guth, S. K. and Eastman, A. A.",
volume="31",
number="11",
pages="567-577",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0002-9408",
doi="",
url="http://dx.doi.org/"
}