- Manuscripts, Latin19
- Manuscripts, Latin (Medieval and modern)10
- Manuscripts, Medieval15
- Manuscripts, Persian1
- Manuscripts, Renaissance26
- Manuscripts, Turkish2
- Mark, Saint1
- Mary, Blessed Virgin, Saint, in the liturgy--Orthodox Eastern Church1
- Massachusetts--Boston1
- Massachusetts--Williamstown3
- Materia medica1
- Medicine2
- Medicine, Greek and Roman1
- Medicine--Study and teaching1
- Memory1
- Menologion (Orthodox Eastern Church)1
- Mercy1
- Metaphysics1
- Metaphysics (Aristotle)2
- Metochites, Theodoros, 1270-13321