@misc{Sylvester_James_Joseph_(1814–1897)_On_1908, author={Sylvester, James Joseph (1814–1897)}, copyright={Public Domain}, address={Cambridge}, howpublished={online}, year={1908}, publisher={Cambridge University Press}, language={eng}, title={On a Theorem relating to polar umbrae}, type={Text}, URL={http://rcin.org.pl/impan/Content/115394/PDF/WA35_140177_11371-2_Art61.pdf}, }