Via http://www.theatrelibrary.org/sibmas/sibmas.html hittar man nu:
The SIBMAS International Directory of Performing Arts Collections and
Institutions lists over 7000 international institutions with material
relating to the performing arts (theatre, opera, music, ballet, film,
circus, radio, television, cabaret, pantomime). Not only basic
information about the institution is provided, but also information
about the collections which are to be found within the institutions.