@article{ref1,
title="Attitudes of air traffic controllers at Frankfurt Airport towards work and the working environment",
journal="Ergonomics",
year="1971",
author="Singer, R. and Rutenfranz, J.",
volume="14",
number="5",
pages="633-639",
abstract="<p>[Abstract unavailable]</p> <p>Language: en</p>",
language="en",
issn="0014-0139",
doi="",
url="http://dx.doi.org/"
}