Duchan, J. S. (2012). Powerful voices: The musical and social world of collegiate a cappella. University of Michigan Press.
Lua i Stíl Chicago (17ú heag.)Duchan, Joshua S. Powerful Voices: The Musical and Social World of Collegiate a Cappella. Ann Arbor: University of Michigan Press, 2012.
Lua MLA (9ú heag.)Duchan, Joshua S. Powerful Voices: The Musical and Social World of Collegiate a Cappella. University of Michigan Press, 2012.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.