Title
- Octoechos1
- Oculus sacerdotis1
- Oedipi et sphingis dialogus1
- Office3
- Office for profession of female Benedictine novices : in Latin with German rubrics].1
- Office lectionary2
- Office of Saint Emmeram1
- Office of the Dead4
- Offices3
- Offices of the Mother of God : in Church Slavic].1
- Officii et magistrati1
- Old Testament1
- Oleum effusum nomine tuum1
- Omnes ad praeda venient1
- Omnis mortalium cura3
- On Catholic faith1
- On Jews living in Rome1
- On accounting and commissions1
- On astronomy, geometry, and arithmetic1
- On being and essence1