Learning to Listen to Music - Critique of Variations on an Original Theme ("Enigma") for Orchestra, Opus 36. - http://www.janedurant.com/learning_to_listen_to_music.htm
Another Musical Enigma - Eric Spierings doesn't claim to solve Elgar's puzzle, but supplies ideas for interpretation. - http://www.uio.no/~ericsp/analyses/elgar.html
Music and Nationalism - Essay from Fordham University's Modern History Sourcebook includes Elgar's Pomp and Circumstance March Number 1 in an examination of the relationship between various compositions and national pride. - http://www.fordham.edu/halsall/mod/NATMUSIC.html