@article{ref1,
title="Special forms of flight. II: helicopters",
journal="British medical journal (clinical research edition)",
year="1983",
author="Harding, R. M. and Mills, F. J.",
volume="287",
number="6388",
pages="346-349",
abstract="<p>[Abstract unavailable]</p><p>Language: en</p>",
language="en",
issn="0267-0623",
doi="",
url="http://dx.doi.org/"
}