@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}, title={Note on a principle in the theory of numbers and the resolubility of any number into the sum of four squares}, type={Text}, URL={http://rcin.org.pl/Content/115298/PDF/WA35_139266_11371-2_Art20.pdf}, }