The modern book collection of the University Library is one of the largest collections of the country, partly due to the fact that in the 18th century the library got a right for a mandatory deposit copy. Before 1949 the library collected materials from every field of science taught at the university. Since 1949 the it collects documents belonging to the humanities, its main fields of interest being history (especially medieval and early modern Hungarian and world history), philosophy and theology. After the foundation of the University Library Service an agreement was laid down between the libraries of the university regarding the field of interest of each library. The acquisition policy of the University Library was constituted according to this agreement.
The card catalogue of the University Library is a complete catalogue of the books entered into the inventory before 1995. This catalogue itself has a historic value, it consists of 3000 book shape boxes with 1.5 million cards, which were digitised recently and made accessible to the readers. (CIPAC – Card Image Public Access Catalogue)
The development of the electronic catalogue of the library has started in 1989, so the documents entered into the inventory after 1989 are available in the online catalogue (OPAC), and at the same time the retrospective electronic cataloguing of documents purchased before 1989 is in process. Therefore it is recommended to start a new search always in the OPAC, and if there is no result and the book sought-after is printed before 1989, it is advisable to continue the search in the CIPAC.