J. Robert Oppenheimer's letter to his brother Frank Oppenheimer (March 12, 1932), as quoted in "Robert Oppenheimer: Letters and Recollections" edited by Alice Kimball Smith (p. 155), 1995.
Thomas Jefferson, Henry Augustine Washington (1854). “The Writings of Thomas Jefferson: Being His Autobiography, Correspondence, Reports, Messages, Addresses, and Other Writings, Official and Private : Published by the Order of the Joint Committee of Congress on the Library, from the Original Manuscripts, Deposited in the Department of State”, p.390
Thorstein Veblen (2016). “THE THEORY OF THE LEISURE CLASS: An Economic Study of American Institutions and a Social Critique of Conspicuous Consumption: Development of Institutions That Shape Society and Influence the Livelihood of Citizens: Based on Sociological & Economical Theories of Charles Darwin, Karl Marx, Adam Smith and Herbert Spencer”, p.48, e-artnow