Author
- Ibn Abi al-Isbaʻ1
- Ibn Battah1
- Ibn Duraid1
- Ibn Khalawayh1
- Ibn al-Ajdābī1
- Ildibrandinus1
- Innocent IV1
- Isidore of Seville1
- Jacobus de Voragine1
- Johan de Arcenay1
- Johannes de Sacrobosco1
- John de Breton1
- John de Seccheville1
- Justinian I1
- Ka'b bin Zuhayr1
- Leo Archpriest1
- Muhammad al-Shaybani1
- Muhammad ibn Ja'far al-Khara'iti1
- Muntajab al-Hamadhānī1
- Muslim ibn al-Ḥajjāj1