Alfie Kohn (1999). “Punished by Rewards: The Trouble with Gold Stars, Incentive Plans, A's, Praise, and Other Bribes”, p.221, Houghton Mifflin Harcourt
Felix Frankfurter, Philip B. Kurland (1970). “Felix Frankfurter on the Supreme Court: extrajudicial essays on the Court and the Constitution”, Belknap Press