@article{ref1,
title="Twenty years and beyond",
journal="Aviation, space, and environmental medicine",
year="1977",
author="Combs, H. B.",
volume="48",
number="8",
pages="745-752",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0095-6562",
doi="",
url="http://dx.doi.org/"
}