@misc{Cayley_Arthur_(1821–1895)_A_1897,
 author={Cayley, Arthur (1821–1895)},
 volume={13},
 copyright={Public Domain},
 address={Cambridge},
 journal={Mathematical papers},
 howpublished={online},
 year={1897},
 publisher={Cambridge University Press},
 language={eng},
 title={A trigonometrical identity},
 type={Text},
 URL={http://www.rcin.org.pl/Content/149095/PDF/WA35_181645_12807-13_Art961.pdf},
}