Encyclopedia of World Biography. « Alexander Graham Bell », Encyclopedia of World Biography. Thomson Gale. 2004. Retrieved December 20, 2009 from Encyclopedia.com.
Schoenherr, Steven. Recording Technology History: Charles Sumner Tainter and the Graphophone, originally published at the History Department of, University of San Diego, revised July 6, 2005. Retrieved from University of San Diego History Department website December 19, 2009. Document transferred to a personal website upon Professor Schoenherr's retirement. Retrieved again from homepage.mac. com/oldtownman website July 21, 2010.