The IAP has a library of 14.000 books. Especially well equipped it is in phenomenology and ancient philosophy. Also in anglophone contemporary metaphysics and (‘analytic’) philosophy of religion it is the best equipped library in the region. The content of the library can be searched with the online catalogue:
Some electronic media can be accessed via Digitale Bibliothek Ostschweiz.
The IAP has the collected manuscripts (Nachlaß) of Dietrich von Hildebrand, Balduin Schwarz, and Siegfried Johannes Hamburger.
If you have questions about the library, contact firstname.lastname@example.org.