@article{ref1,
title="Sans serif letters for Snellen charts",
journal="JAMA journal of the American Medical Association",
year="1970",
author="Deederer, C.",
volume="211",
number="10",
pages="1699-1699",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0098-7484",
doi="",
url="http://dx.doi.org/"
}