The Répertoire International des Sources Musicales (RISM) - International Inventory of Musical Sources - is an international, non-profit organization that aims to comprehensively document extant musical sources worldwide: manuscripts, printed music editions, writings on music theory, and libretti that are found in libraries, archives, churches, schools, and private collections. RISM Online, a service from the RISM Digital Center provides access to these musical sources through extensive search and browse functions. Multiple entry points, with extensive Source, Person, and Institution search interfaces, provide users with the ability to quickly narrow down relevant results using several different approaches, including keyword searches, filters, and relationship information.