Drawing, Art of Love: Nearly 100 Sex Positions and Wealth of Illustrated Material from Foreplay to Anatomy, e-book, Mobilereference.com, 2007, ISBN9781605011172, n.p.
Psychiatric Research Report: 6-9, American Psychiatric Association, 1957, p. 34.
Fear of Being Fat: The Treatment of Anorexia Nervosa and Bulimia, ed. C. Philip Wilson with Charles C. Hogan and Ira L. Mintz, Classical psychoanalysis and its applications, New York: Aronson, 1983, ISBN9780876684801, p. 145.
David J. Linden, The Compass of Pleasure: How Our Brains Make Fatty Foods, Orgasm, Exercise, Marijuana, Generosity, Vodka, Learning, and Gambling Feel so Good, New York: Viking-Penguin, 2011, ISBN9780670022588, n.p.: the example that follows involves water from a garden hose rather than the mouth.
Todd K. Shackelford, The Cambridge Handbook of Evolutionary Perspectives on Sexual Psychology Volume 4: Controversies, Applications, and Nonhuman Primate Extensions, Cambridge University Press, 2022, ISBN978-1-10895-243-9, n.p.