De revolutionibus, libri VI (manuscript)
(lat.)
at Biblioteka Jagiellońska
[www.bj.uj.edu.pl/bjmanus/revol/toc_e.html]

De revolutionibus, libri VI (excerpt : book 1)
(engl.: E. Rosen)
at WebExhibits
[webexhibits.org/calendars/year-text-Copernicus.html]