Title
- Oleum effusum nomine tuum1
- On Catholic faith1
- On being and essence1
- On buying and selling1
- On diphthongs1
- On the eternity of the world1
- On virtue1
- Operationes Ihesu Christi1
- Ophthalmology text1
- Oratio in laudem rei publicae venetorum1
- Orationes ; In C. Sallustium Invectiva and Oratio ad Romanos ; In M. Tullium Ciceronem Invectiva.1
- Orator ad Brutum1
- Order for peaceable behavior1
- Ordinatio totius officii divini1
- Ordo dedicationis ecclesiae et altaris1
- Ordo judiciorum1
- Organon1
- Otia imperialia1
- Painting1
- Palimpsest leaf from manuscript antiphonal.1