Albert Einstein (2015). “Bite-Size Einstein: Quotations on Just About Everything from the Greatest Mind of the Twentieth Century”, p.33, St. Martin's Press
Winston Churchill's speech to the Scottish Unionist Association in Edinburgh, Scotland (September 25, 1924), later published in "Winston S. Churchill: His Complete Speeches, 1897-1963" edited by Robert Rhodes James (Volume 4, p. 3472), 1974.
Samuel Taylor Coleridge (1858). “The complete works of Samuel Taylor Coleridge: With an introductory essay upon his philosophical and theological opinions”, p.222