@article{ref1,
title="Operational Research into Air Traffic Control",
journal="Operational research quarterly (1950)",
year="1950",
author="Bell, G. E.",
volume="1",
number="2",
pages="24-24",
abstract="<p>[Abstract unavailable]</p>",
language="",
issn="1473-284X",
doi="",
url="http://dx.doi.org/"
}