A-R Editions' Online Music Anthology is extensive collection of examples designed expressly for music history courses. A-R's Online Music Anthology contains at least twice as many pieces as print anthologies, all newly engraved and available online.
"The online sheet music library is a part of e-concerthouse virtual library. The online sheet music library is maintained by OUAS library information officer Tiina Tolonen. In the present stage the library is based on the personal collection of lecturer Kari Kuosmanen, which consists of thousands of notes. This collection can not be published in its entirety for copyright reasons." This site "has all the Schubert Lieder (besides many other things) in fully transposable Sibelius files. The search engine is not too good (so search for example just with "trauer" and "perle" respectively)."
The David M. Rubenstein Rare Book & Manuscript Library at Duke University holds a significant collection of 19th and early 20th century American sheet music. The Historic American Sheet Music Project provides access to digital images of over 3000 pieces from the collection, published in the United States between 1850 and 1920.
The Howard W. Wildin Sheet Music Collection contains 18,584 pieces, mainly of original American popular sheet music dating back to the mid-19th century including several hundred published musical and film song folios, musical artist folios, musical genre folios, and dance folios. Some pieces from different countries are also part of the collection.
IMSLP, also known as the International Music Score Library Project or Petrucci Music Library, was started in 2006 with the goal of freely providing music scores. It has expanded to provide scores, recordings, and analyses with an ultimate goal of gathering all public domain scores and music released to the public. On the main page, visitors may search for works by composer (or composer's nationality), genre, time period, or difficulty.
A unified index to a broad group of digitized sheet music collections, including contributions by Duke University, Johns Hopkins, Indiana University, and UCLA. Useful to researchers interested in sheet music and to social historians.