Margaret Sanger, Michael W. Perry, H. G. Wells (2003). “The Pivot of Civilization in Historical Perspective: The Birth Control Classic”, p.40, Inkling Books
Thorstein Veblen (2016). “THORSTEIN VEBLEN Ultimate Collection: 8 Books & 50+ Business Essays and Articles in Warfare and Economics: The Theory of the Leisure Class, The Theory of Business Enterprise, The Higher Learning In America, Panem et Circenses, The Vested Interests and the Common Man, The Use of Loan Credit in Business…”, p.16, e-artnow