(en) Derek B. Scott, Dayton Street Funk: The Layering of Musical Identities, Ashgate Publishing, (ISBN9780754664765, lire en ligne), p. 275.
Michael Stephen Hanson, People Get Ready: Race, Place and Political Identity in Post-civil Rights Black Popular Music, 1965-1975, UC Berkeley, (lire en ligne), p. 124.
(en) William Echard, Psychedelic Popular Music: A History through Musical Topic Theory, Indiana University Press, , 123–125 p. (ISBN9780253026590, lire en ligne)