Author
- Osbern of Gloucester1
- Papias1
- Philip the Chancellor1
- Piccolomini1
- Piccolomo Oltremonti1
- Pietro Parenzi1
- Podestà of Monticchiello (Italy)1
- Prosper of Aquitaine1
- Pseudo-Hippocrates1
- Ptolemy1
- Qadi Ayyad1
- Rabīʻah ibn Muḥammad Maʻmarī1
- Raginaldus Collus Rubeus1
- Ricardus, de Mediavilla, approximately 1249-1308?1
- Richard Fishacre1
- Richard de Geveldale1
- Robert de Gretham1
- Roger Bigod, 2nd Earl of Norfolk1
- Rogerius1
- Rolandino de' Passaggeri1