@article{ref1,
title="Some problems in vision regarded with respect to linearity and frequency response",
journal="Annals of the New York Academy of Sciences",
year="1961",
author="van der Tweel, L. H.",
volume="89",
number="5",
pages="829-856",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0077-8923",
doi="10.1111/j.1749-6632.1961.tb20181.x",
url="http://dx.doi.org/10.1111/j.1749-6632.1961.tb20181.x"
}