Ralph Waldo Emerson, Robert Ernest Spiller, Alfred Riggs Ferguson, Wallace E. Williams, Joseph Slater (1987). “The Collected Works of Ralph Waldo Emerson: Representative men: seven lectures”, p.18, Harvard University Press
"Rain Still Follows Him: The President's Vermont Trip Marked by Storms". Speech in Rutland, Vermont, reported in The New York Times, August 29, 1891 issue p. 5,
Ralph Waldo Emerson, Robert Ernest Spiller, Alfred Riggs Ferguson, Wallace E. Williams, Joseph Slater (1987). “The Collected Works of Ralph Waldo Emerson: Representative men: seven lectures”, p.18, Harvard University Press
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.439, Harriman House Limited