Thomas Hobbes (1750). “The Moral and Political Works To which is Prefixed the Autors Life, Extracted from that Said to be Written by Himself ... Illustr. by the Ed. - London 1750”, p.107
Marshall McLuhan, W. Terrence Gordon, Elena Lamberti, Dominique Scheffel-Dunand (2011). “The Gutenberg Galaxy: The Making of Typographic Man”, p.208, University of Toronto Press