• Art Song Central
Free, printable sheet music for singers and voice teachers. An emphasis is placed on standard classical and traditional repertoire.
• The Choral Public Domain Library
Searchable database of close to nine thousand choral music scores available for free download. Updated daily. Also includes texts and translations.
• IMSLP/Petrucci Music Library
The free public domain sheet music library. 385,000 scores available for pdf download.
• Mutopia Project
2070 pieces of music – free to download, modify, print, copy, distribute, perform, and record – all in the Public Domain or under Creative Commons licenses.
• Neue Mozart-Ausgabe (NMA)
An ongoing project to digitize the complete works of Mozart and make them available. Users must agree to "fair use" principles of copyright law.
Many libraries have begun digitizing their primary source materials. Once you know which library owns a specific manuscript or edition, check the library's website to see if a digital image is available.