Schaff, Philip: The New Schaff-Herzog Encyclopedia of Religious Knowledge, vol. XI, s. 422–423. Grand Rapids, Michigan: Baker Book House, 1953. Teoksen verkkoversio. (englanniksi)
Saint Peter's Basilica.org: Saint Peter's in 1505, James Lees-Milne (1967). Viitattu 25.9.2007. ”In 1513 the pope issued a bull announcing to the world that the new basilica would eclipse in size and magnificence every church in Christendom. Graciously he promised an extension of indulgences to those pious benefactors who agreed to pay contributions on an annual basis”. (englanniksi).