Richard Whately (1855). “Introductory lectures on political-economy, delivered at Oxford, in Easter term MDCCCXXXI. With remarks on tithes and on poor-laws and on penal colonies”, p.64
Richard Whately (1846). “Elements of Rhetoric: Comprising an Analysis of the Laws of Moral Evidence and of Persuasion, with Rules for Argumentative Composition and Elocution”, p.394