@Article{BVMC:225820, author = {Fita, Fidel}, title = {Bula inédita de Silvestre II}, journal = {Boletín de la Real Academia de la Historia. Tomo 18, Año 1891}, publisher = {Alicante : Biblioteca Virtual Miguel de Cervantes, 2005}, year = {2005}, url = {https://www.cervantesvirtual.com/nd/ark:/59851/bmc8w3r2} }