Former Owner
- Oswald Carl Friedrich von Seilern und Aspang1
- Otto Orren Fisher1
- Otto Vollbehr1
- P. J. De Mat1
- Pascal Gay1
- Paul Gottschalk1
- Pease, John William, 1820-19001
- Peter Arrell Brown Widener1
- Petrus Giraud1
- Petrus Hofstede1
- Philadelphia Rare Books & Manuscripts Company1
- Philip C. Duschnes1
- Philip C. Duschnes Rare Books & First Editions1
- Philip Hurd1
- Philip Kerr, 11th Marquess of Lothian1
- Philippe Hurault de Cheverny1
- Philippe de Béthune1
- Phyllis Walter Goodhart Gordan1
- Pierleone Leoni1
- Pierre Gorman1