Title
- Oculus sacerdotis1
- Office1
- Office of the Dead1
- Officii et magistrati1
- Officium dicendum in ecclesiola supra illos, qui damnati sunt ad mortem1
- Ogasawara-den saiku kata kikigaki1
- Omnes ad praeda venient1
- Omnis mortalium cura3
- On accounting and commissions1
- On charms and talismans1
- Opuscula2
- Orations2
- Ordo judicarius1
- Organon1
- Orthographia1
- Ottoman Turkish expansion on qaṣīdat al-Burdah1
- Paludi pontine1
- Pand-i ʻAṭṭār1
- Panormia1
- Papal bull2