Walter Lippmann, Clinton Rossiter, James Lare (1982). “The Essential Lippmann: A Political Philosophy for Liberal Democracy”, p.233, Harvard University Press
John James Audubon (1831). “Ornithological Biography, Or an Account of the Habits of the Birds of the United States of America: Accompanied by Descriptions of the Objects Represented in the Work Entitled The Birds of America, and Interspersed with Delineations of American Scenery and Manners”, p.7