Author
- Pietro Cavallini1
- Pietro Paolo Muscarello1
- Pietro de' Crescenzi1
- Pius II1
- Pius III1
- Priscian1
- Procopius1
- Prosdocimus de Beldemandis1
- Pseudo-Bede1
- Pseudo-Dionysius the Areopagite1
- Pseudo-Eusebius of Cremona1
- Pseudo-Jerome1
- Pseudo-Joachim of Fiore1
- Pseudo-Seneca1
- Publius Papinius Statius1
- Quintus Curtius Rufus1
- Richard Maidstone1
- Rocca, Antonio1
- Roman Catholic Archdiocese of Siena1
- Rudulphus Bollartus1