Adam Smith (1817). “The Theory of Moral Sentiments: Or, An Essay Towards an Analysis of the Principles by which Men Naturally Judge Concerning the Conduct and Character, First of Their Neighbours, and Afterwards of Themselves : to which is Added, A Dissertation on the Origin of Languages”, p.550
Adam Smith (2007). “The Wealth of Nations: An Inquiry Into the Nature and Causes of the Wealth of Nations: With an introduction by Jonathan B. Wight, University of Richmond”, p.393, Harriman House Limited