The Library of Congress Aaron Copland Collection
Part of the American Memories Project, this website includes links to the featured items in the Aaron Copland collections, including visual images and texts of personal letters, his own writings, his sketches and manuscripts of music, and photographs. An extensive and thorougly organized primary source on the music of Copland. Also includes an index and a search screen.
http://memory.loc.gov/ammem/achtml/achome.html

The Library of Congress Leonard Bernstein Collection
“This online Leonard Bernstein Collection makes available a selection of 85 photographs, 177 scripts from the Young People’s Concerts, 74 scripts from the Thursday Evening Previews, and over 1,100 pieces of correspondence, in addition to the collection’s complete Finding Aid.”
http://memory.loc.gov/ammem/lbhtml/

The Library of Congress Mario Castelnuevo-Tedesco Collection
Papers of Mario Castelnuevo-Tedesco are held in the Library of Congress. Included are: “manuscript and printed music, programs, reviews of Castelnuovo- Tedesco’s music, contracts, photographs and related materials. In addition, the collection includes correspondence from many of the 20th century’s major musical figures…”
http://www.loc.gov/today/pr/2000/00-114.html