The Library also holds large loan collections with thousands of early printed books – such as the library of the Maatschappij der Nederlandse Letterkunde (since 1876) and the Bibliothèque Wallonne (since 1998) – and cooperates with the Bibliotheca Thysiana, situated at Rapenburg 25, whose collections are to be consulted in the Special Collections Reading Room. This library was founded by testament in 1653 by the young Dutch jurist Johannes Thysius. It is the only Dutch private book collection from the seventeenth century which is housed in the original purpose-built library.

• Books printed before 1501 (incunabula)
• Books printed in Leiden
• Publications by Leiden professors
• Theses of Leiden University
• Pamphlets
• Ephemeral printed works
• Printed sources regarding Dutch linguistics and literature
• Printed sources regarding the history of the Netherlands (especially the Eighty Years War)
• History of protestantism

Catalogue, Collection Guides and Digital Special Collections

All early printed books can be found through the Catalogue, along with: 

• Collection guides: records with information on separate collections containing early printed books, for example: – Bibliotheca Thysiana (pamphlets). – Bibliothèque Wallonne (Walloon Churches in the Netherlands). – G.J. Boekenoogen (1868-1930), folklorist. – Emblem books. – Ephemeral printed works. – Incunabula. – Parish library Kethel. – Parish Library Noordwijk (Groenhout). – Parish Library Langeraar. – Maatschappij der Nederlandse Letterkunde (Society of Dutch Literature). – P.A. Locatelli (1696-1774), composer. – P. Marchand (1678-1756), huguenot/bookseller. – E.M.  Meijers (1880-1954), jurist. – Dutch Reformed Church. – Remonstrant Seminary. – D. Ruhnkenius (1723-1789), classical scholar. – Printed Resolutions of the States-General and other official documents from the time of the Republic. – I. Vossius (1718-1689), classical scholar. – J.J. Wepfer (1620-1695), medical scholar.
• Titles of digital copies, for instance:
  – Digitized copies of chapbooks (Boekenoogen Collection) and ephemeral printed works from the University Library; click the link View Online to examine them in Digital Collections.

Printed Catalogues

In the course of time many catalogues have been realized. They have been brought together in a separate collection guide: Catalogues of the Holdings of Leiden University Libraries. Here about four hundred printed publications are offered, divided in chapters (A-S), and with links to the copies on paper or digitized versions.

Originally the printed works were described together with the manuscripts in a number of general catalogues (A 1-9), representing the entire collection of the Library. These catalogues are a first aid to examine when a certain book was obtained by the Library.

Library Archives and Reference Library

More information about the acquisition and provenance of early printed books is to be found in the archives of the Library. Consult the collection guides University Library Archives (sections A, C, G, J, L and V) and Archive of the Maatschappij der Nederlandse Letterkunde (section B, and supplement B 212-215). Especially the there indicated journals and acquisition lists are important sources, next to the printed library catalogues.

The Special Collections Reference Library at entrance 4 of the second floor (go right) contains journals, reference works, bibliographies, surveys and library catalogues pertaining to western and oriental manuscripts and rare books. The volumes are shelved according to the Library of Congress Classification. The LCC-shelfmarks in the catalogues and on the spine labels differ frome those of the Study Area (first floor) in that they begin with: “II-4”. Important subjects:

• Literature on the history of the production and distribution of the printed book (Z116-659) and libraries in general (Z772-1000.5);
• Bibliographies regarding the printed book: general (Z1001-1121), by country (Z1201-4980).

Internet Selection

• Short Title Catalogue Netherlands (STCN) — Database with records of books printed within the borders of the presentday Kingdom of the Netherlands in the period 1540-1800. Including short descriptions of Dutch (post-)incunables.
• Bibliopolis (KB) – History of the printed book in the Netherlands.
• Short Title Catalogue Vlaanderen (STCV) — Database with records of books printed in Flanders until 1801.
• Gesamtkatalog der Wiegendrucke (GW) — Database with records of European books printed before 1501.
• Glossary of Early Modern Print Genres (Universiteit Utrecht) - Covers terminology in English, Dutch, French, German, Italian, and Spanish. 
• Incunabula Short Title Catalogue (ISTC) — Database with records of European books printed before 1501.
• Universal Short Title Catalogue (USTC) — Database with records of European books printed before 1601.
• Heritage of the Printed Book Database (HPD) — Database with records of early printed books (1455-1830) held by important European and American research libraries
• WorldCat — Online catalogue on more then 50.000 libraries from 90 countries.
• Digital versions of printed works present in Leiden University Library can be consulted in Delpher, and as well in Google Books.