O’Malley. Giles of Viterbo: A Reformer’s Thought on Renaissance Rome // Rome and the Renaissance: Studies in Culture and Religion. London: Variorum Reprints, 1981.

O’Malley. Fulfilment of the Christian Golden Age Under Pope Julius II. – O’Malley John W. Fulfilment of the Christian Golden Age Under Pope Julius II: Text of a Discourse of Giles of Viterbo, 1507 // Traditio. 1969. P. 265–338.

O’Malley. Giles of Viterbo on Church and Reform. – O’Malley John W. Giles of Viterbo on Church and Reform: A Study in Renaissance Thought. Leiden: E. J. Brill, 1968.

O’Malley. The Vatican Library and the School of Athens. – O’Malley John W. The Vatican Library and the School of Athens: A Text of Battista Casali, 1508 // Journal of Medieval and Renaissance Studies. 1977.

Oppe. Raphael. – Oppe A. P. Raphael / Ed. Charles Mitchell. London: Elek Books, 1970.

Ostermark-Johansen Lene. Sweetness and Strength: The Reception of Michelangelo in Late Victorian England. Aldershot, Hants.: Ashgate, 1998.

Ottavia. High and Low Prophetic Culture in Rome. – Ottavia Niccoli. High and Low Prophetic Culture in Rome at the Beginning of the Sixteenth Century // Reeves. Prophetic Rome in the High Renaissance Period.