1. National health expenditures;Letsch;Health Care Financing Review,1988
2. Disability, utilization, and costs associated with musculoskeletal conditions, United States, 1980;Murt,1986
3. Variations in the incidence of surgery;Lewis;N Engl J Med,1969
4. Variation in medical care among small areas;Wennberg;Sci Am,1982
5. Does inappropriate use explain geographic variations in the use of health care services?;Chassin,1987