@article{ref1,
title="Relation of the Brightness Differences of Colors to their Apparent Distances",
journal="Journal of psychology, The",
year="1948",
author="Johns, Eugene H. and Sumner, F. C.",
volume="26",
number="1",
pages="25-29",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="0022-3980",
doi="10.1080/00223980.1948.9917393",
url="http://dx.doi.org/10.1080/00223980.1948.9917393"
}