Blech, Benjamin; Doliner, Roy. (2008). The Sistene Secrets. New York, NY: HarperCollins Publishers. m/s. 106. ISBN978-0-06-146904-6. The term 'terrible' was first applied by Julius himself to Michaelangelo, and only later to the Pope by others: Pastor 1902.
Kühner, Hans (2013). "Julius II". Encyclopædia Britannica. Encyclopædia Britannica Inc. Dicapai pada 7 October 2013.
newadvent.org
Indulgences (which remit the temporal effects of sins that have already been forgiven) involve the person receiving the indulgence performing a penance of some kind, such as performing a certain devotional practice or doing some sort of good work, which can take the form of donating to a charitable cause. Kent, William. "Indulgences". The Catholic Encyclopedia. New York: Robert Appleton Company. Dicapai pada 26 May 2020..