@article{ref1,
title="Maximum flying time for air crews",
journal="Journal of aviation medicine",
year="1949",
author="Hannisdahl, B.",
volume="20",
number="4",
pages="257-259",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0095-991X",
doi="",
url="http://dx.doi.org/"
}