John Cotton Dana's remarks on a quotation suitable for inscription on a new building at Newark State College, Union, New Jersey (1912) as quoted in "The New York Times Book Review" (p. 55.), March 5, 1967.
Albert Einstein, Stephen W. Hawking (2007). “A Stubbornly Persistent Illusion: The Essential Scientific Works of Albert Einstein”, p.346, Running Press
Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.32, St. Martin's Press