Killing for Company, by Brian Masters. New York: Dell, 1993. (Originally published in Britain in a different form in 1985.)
Murder by Numbers: British Serial Sex Killers since 1950 by Anna Gekoski. London: Andre Deutsch, 1998
The A-Z Encyclopedia of Serial Killers, by Harold Schecter and David Everitt. New York: Pocket, 1996.
The Killers Among Us, by Colin Wilson. New York: Warner, 1995.
Human Monsters, by David Everitt. New York: Contemporary Books, 1993.
The Encyclopedia of Serial Killers, by Brian Lane and Wilfred Gregg.
New York: Berkley, 1992.