@article{ref1,
title="Intermediate vision testing of airline pilots",
journal="Aerospace medicine",
year="1966",
author="Harper, C. R. and Keehan, J. E. and Kidera, G. J.",
volume="37",
number="8",
pages="841-843",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0001-9402",
doi="",
url="http://dx.doi.org/"
}