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
Thomas Hobbes, John Charles Addison Gaskin (1999). “The Elements of Law, Natural and Politic: Part I, Human Nature, Part II, De Corpore Politico ; with Three Lives”, p.77, Oxford University Press, USA