Kühnhold, Wolfgang (1998). "Meyerbeer's Robert Le Diable: The First Singers of Robert and the 'Mario-Aria' at the Beginning of Act 2 (1998)", written for the Meyerbeer Fan Club, 15 May 1998. Reprinted, as revised by Robert Letellier on 28 July 2007, in Letellier 2007, pp. 534–542.
Letellier, Robert Ignatius. Editor (2007). Giacomo Meyerbeer: A Reader. Newcastle, UK: Cambridge Scholars Publishing. ISBN978-1-84718-388-0.
Pleasants, Henry (1966),The Great Singers: From the Dawn of Opera to Our Present Time. New York: Simon & Schuster. ISBN0-671-20612-5
Sumber lain
Beale, Thomas Willaert (1890), The Light of Other Days, London: Richard Bentley and Son.