Margaret Sanger, Michael W. Perry, H. G. Wells (2003). “The Pivot of Civilization in Historical Perspective: The Birth Control Classic”, p.345, Inkling Books
George Washington, John Jay, Jared Sparks (1850). “Washington's Farewell Address to the People of the United States of America”, p.38, New York : J. Wiley
Jeremy Bentham (1834). “Deontology: or, The science of morality: in which the harmony and co-incidence of duty and self-interest, virtue and felicity, prudence and benevolence, are explained and exemplified”, p.131