ACE is a searchable database that contains information on compositions in the ASCAP repertory that have appeared in ASCAP's domestic performance surveys, including foreign compositions licensed by ASCAP for public performance in the United States, as well as most works registered with ASCAP since January 1991, whether surveyed or unsurveyed. ACE may also be used to determine whether a particular composer, songwriter or music publisher is a member of ASCAP.

The Bagaduce Library has over 215,000 music titles and over 1 million pieces of music. You can purchase sheet music from their collection via their online catalog (they'll send you copies that is.)

Digitized sheet music from a collection of ca. 60,000 items of sheet music, much of which is pre-1875.

Any Song or Musical Work Published in 1922 or Earlier is in the Public Domain in the USA. No Sound Recordings are PD in the USA due to a tangled complexity of Federal and State Law.

The catalogue indexes manuscripts and printed anthologies produced between 1475 and 1600; contains an estimated 33,000 motet and Mass Proper appearances.

The free online version of RISM. Takes advantage of the rich metadata that RISM carefully provides.

This acts as a meta-search for IMSLP and other large scores online websites.

This site is a source of sheet music published in Canada before 1921, selected from Library and Archives Canada's historical collection.