1. Schweitzer A: On the Edge of the Primeval Forest. New York, Macmillan, p 62, 1931.
2. Bonica, JJ: The Management of Pain, 2nd ed. Philadelphia, Lea & Febiger, 1990.
3. National Center for Health Statistics: Current Estimates from the National Health Interview Survey. United States, 1988. DHSHS Publication No. (PHS) 89. Hyattsville, MD, National Center for Health Statistics, 1989.
4. Bonica JJ: Biology, pathophysiology, and treatment of acute pain. In: Persistent Pain, Vol. 5, Lipton S, Miles J (eds.). Grune & Stratton, Orlando, p 1, 1985.
5. Bonica JJ: General considerations of acute pain. In: Bonica JJ: The Management of Pain, 2nd ed. Philadelphia, Lea & Febiger, p.159, 1990.