@article{1969,
volume={312},
ISSN={0080-4630},
url={http://dx.doi.org/10.1098/rspa.1969.0144},
DOI={10.1098/rspa.1969.0144},
number={1508},
journal={Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences},
publisher={The Royal Society},
year={1969},
month=aug,
pages={99–128} }