Benjamin Franklin, Edmund Sears Morgan (2007). “Not Your Usual Founding Father: Selected Readings from Benjamin Franklin”, p.119, Yale University Press
Benjamin Franklin's letter to David Hartley (December 4, 1789) as quoted in "The Writings of Benjamin Franklin," Volume 10 (p. 72) edited by Albert H. Smyth, 1907.
Benjamin Franklin, Henry Stueber, Benjamin Franklin Collection (Library of Congress) (1794). “Works of the late Dr. Benjamin Franklin: consisting of his life, written by himself : together with essays, humourous, moral & literary, chiefly in the manner of the Spectator : in two volumes”