@article{ref1,
title="Visual workload of the copilot/navigator during terrain flight",
journal="Human factors",
year="1979",
author="Sanders, M. G. and Simmons, R. R. and Hofmann, M. A.",
volume="21",
number="3",
pages="369-383",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0018-7208",
doi="",
url="http://dx.doi.org/"
}