1. Benedetti F, Amanzio M. The neurobiology of placebo analgesia: from endogenous opioids to cholecystokinin. Prog Neurobiol. 1997;52(2):109–25.
2. Benson H. Timeless healing: the power and biology of belief. New York: Simon and Schuster; 1996.
3. Berger JT. Placebo medication use in patient care: a survey of medical interns. West J Med. 1999;170:93–6.
4. Brody H. Placebos and the philosophy of medicine. Chicago: University of Chicago Press; 1980.
5. Ernst E, Abbot NC. Placebos in clinical practice: results of a survey of nurses. Perfusion. 1997;10:128–30.