Here you will find several relevant meta catalogs, which allow you to search multiple catalogs at the same time:
A web portal of eleven research institutes in the area of Beyoğlu/Istanbul with a common library catalog.
The KVK is a meta catalog for the identification of several hundred million media in catalogs worldwide.
The national catalog of academic libraries. For technical reasons, not all universities participate. The non-participating universities can be researched in the Yordam catalog (see below).
Virtual catalog of SSG Middle East/North Africa
A meta catalog of the SSG 6.23 Middle East including North Africa, the database Internationale Beziehungen und Länderkunde (IBLK), the Friedrich-Ebert-Stiftung, the Zentrum Moderner Orient, Berlin, the Orient-Institut Beirut, and the Orient-Institut Istanbul.
A directory of manuscripts in Turkey. Meta catalog of currently approx. 30 manuscript libraries in Turkey; simple catalog search possible without registration, with registration page views, etc. The Süleymaniye catalog is not integrated. This catalog provides direct access to digital copies of some of the manuscripts. For this, registration is required. Downloads and prints are charged a fee!