@misc{Cayley_Arthur_(1821–1895)_On_1897, author={Cayley, Arthur (1821–1895)}, volume={13}, copyright={Public Domain}, journal={Mathematical papers}, address={Cambridge}, howpublished={online}, year={1897}, publisher={Cambridge University Press}, language={eng}, type={Text}, title={On the focals of a quadric surface}, URL={http://rcin.org.pl/impan/Content/144984/PDF/WA35_176637_12807-13_Art902.pdf}, }