Title
- On the eternity of the world1
- On the martrydom of Ḥusayn1
- On virtue1
- Operationes Ihesu Christi1
- Ophthalmology text1
- Opisanīe novyi͡a zemli Sibirskago gosudarstva, v" kotoroe ono vremi͡a i kakim" sluchaem" dostalos' za Moskovskoe gosudarstvo, i kakoe toĭ zemli︠e︡ polozhenīe1
- Opus pacis1
- Opusculum de formandis epistolis1
- Opusculum de multiplici ludo1
- Or ha-sekhel and Sefer ha-Shem1
- Oratio ad immortalitatem illustriassimae nec non famigerratissimae laudis1
- Oratio in laudem rei publicae venetorum1
- Orationes in Laurentium Vallam1
- Orator ad Brutum1
- Order for peaceable behavior1
- Order of Extreme Unction1
- Order of the Egyptian Fathers1
- Ordinary of arms1
- Ordinatio totius officii divini1
- Ordo benedicendi oleum catechumenorum et infirmorum et conficiendi chrisma1