Giacomo Meyerbeer, Robert Ignatius Letellier (1999). “The Diaries of Giacomo Meyerbeer: The years of celebrity, 1850-1856”, p.21, Fairleigh Dickinson Univ Press
Lord Philip Dormer Stanhope Chesterfield, Philip Dormer Stanhope Earl of Chesterfield (1855). “The Works of Lord Chesterfield: Including His Letters to His Son, Etc : to which is Prefixed, an Original Life of the Author”, p.497