Title
- Oratio ad immortalitatem illustriassimae nec non famigerratissimae laudis1
- Oratio in laudem rei publicae venetorum1
- Orationes3
- Orations4
- Orator ad Brutum1
- Order2
- Order for peaceable behavior1
- Order of the Egyptian Fathers1
- Ordinal5
- Ordinances4
- Ordinary of the Mass4
- Ordinatio totius officii divini1
- Ordo benedicendi oleum catechumenorum et infirmorum et conficiendi chrisma1
- Ordo dedicationis ecclesiae et altaris1
- Ordo exsequiarum1
- Ordo judicarius2
- Ordo judiciorum1
- Ordo missae2
- Organon1
- Otia imperialia1