Twentieth Century

http://www.cyberbee.com/edison/cylinder.html
MP3 recordings of popular songs from 1900-1919 originally recorded on wax cylinder.

hhttp://historymatters.gmu.edu/mse/Songs/
Resources for teaching American popular song. Includes an annotated bibliography.

http://jpaubel.chez-alice.fr/caricatures.htm
Caricatures of nineteenth and twentieth century composers. Most are recognizable; some are identified by name, some not.

http://lcweb2.loc.gov/ammem/browse/ListSome.php?category=Performing%20Arts,%20Music
Links to documents, recordings, and photographs from the Library of Congress.

http://memory.loc.gov/ammem/afccchtml/cowhome.html
Recordings, images, and correspondence relating to folk music in 1930s Northern California.

http://memory.loc.gov/ammem/wwghtml/wwghome.html
Woody Guthrie's correspondence with the Archive of American Folk Song.

http://www.dismuke.org/
Audio files of ragtime, jazz, dance music, and opera from 1900-1940.

http://www.jaytomlin.com/music/settheory/help.html#forte
Brief introduction to the terms and techniques of set theory. Accompanies a java applet that allows users to calculate normal order, prime form, interval vector, and Forte number.

http://www.lib.virginia.edu/small/exhibits/music/index.html
University of Virginia collection of audio files and manuscripts. Features hymns and spirituals, protest songs, and minstrelsy.

http://www.obsolete.com/120_years/
Detailed information about obscure electronic instruments. Includes audio and video files, which are highly recommended.