International History of the Recording Industry. Continuum. p. 32. ISBN 978-0-304-70590-0. Tosches, Nick (1996). Country: The Twisted Roots Of Rock 'n' Roll...
International History of the Recording Industry. A&C Black. p. 53. ISBN 978-0-304-70590-0. Bryan Randolph Gilliam (1994). Music and Performance During the Weimar...