1. The physicians service industry;Rayack,1971
2. National Health Expenditures, 1982;Gibson;Health Care Financing Rev,1983
3. Economic growth in the US dental industry, 1950–1977;Doherty;J Dent Educ,1981
4. Economics;Lipsey,1981
5. US Department of Commerce. Survey of current business. Washington, DC, Government Printing Office.