@misc{Sylvester_James_Joseph_(1814–1897)_Note_1908, author={Sylvester, James Joseph (1814–1897)}, copyright={Public Domain}, address={Cambridge}, howpublished={online}, year={1908}, publisher={Cambridge University Press}, language={eng}, type={Text}, title={Note on the periodical changes of orbit, under certain circumstances, of a particle acted on by a central force, [...]}, URL={http://www.rcin.org.pl/Content/115429/PDF/WA35_140243_11371-2_Art89.pdf}, }