"Biographies of Distinguished Scientific Men". Book by François Arago, as translated by Baden Powell, Robert Grant, and William Fairbairn, p. 365, 1859.
Charles Sanders Peirce (1933). “Collected Papers of Charles Sanders Peirce: Exact logic (Published papers).. The Simplest mathematics”, Harvard University Press
Arthur Conan Doyle (2007). “The New Annotated Sherlock Holmes: The Complete Short Stories: The Adventures of Sherlock Holmes and The Memoirs of Sherlock Holmes (Non-slipcased Edition) (Vol. 1) (The Annotated Books)”, p.151, W. W. Norton & Company