Britten-Pears Foundation (Britten estate and Britten-Pears Library; articles about Britten's life and works; online thematic catalogue (in progress); large archival collections)
BBC Audio Interviews: Benjamin Britten (excerpts from "The Composer Speaks," August 7, 1957, and "Radio Newsreel," November 21, 1963) (No longer available)
Images of Britten (National Portrait Gallery)
Benjamin Britten: Poetry, Politics, and Sound (from poets.org; emphasis on War Requiem)
Britten at the Lied and Art Song Texts Page
National Register of Archives (descriptions and links to archival collections)
(Below not found - discovery.lib.harvard.edu)
Ford, Boris, ed. Benjamin Britten's Poets: The Poetry He Set to Music. Manchester, England: Carcenet, 1994. (anthology of texts, with notes on first performances)
Hodgson, Peter J. Benjamin Britten: A Guide to Research. New York: Garland, 1996.