Former Owner
- Judith Lady Montefiore College1
- Jules Bonhomme1
- Julie Florence de Cossette1
- Katholieke Universiteit te Leuven Universiteitsbibliotheek1
- Kenneth Hyde1
- Klaus Dieter Dahmen1
- Konrad von Maurer1
- Kulturhistorisches Museum Magdeburg1
- Lady Margaret Ayloffe1
- Lambach Abbey1
- Lambertus Eerens1
- Lancino Curti1
- Lathrop Colgate Harper1
- Laura Hurd Motion1
- Laurence Kirby1
- Law Society1
- Lawrence J. Schoenberg16
- Leicester Harmsworth1
- Leo Olschki3
- Leonardus Martinotius1