^Michael Kennedy (2002). Marian Anderson: A Singer's Journey. University of Illinois Press. p. 174. ISBN0-252-07067-4.
^Michael Kennedy (2010). Glyndebourne: A Short History. Shire Publications. p. 21. ISBN978-0-7478-0821-3.
^Ruth-Esther Hillila, Barbara Blanchard Hong (1997). Historical Dictionary of the Music and Musicians of Finland. Greenwood. p. 333. ISBN0-313-27728-1.