1. 1990 Census of Population and Housing Summary,1993
2. 1990 Guide to the Health Care Field,1990
3. Production, information costs and economic organization;Alchian;The American Economic Review,1972
4. Cost comparisons of proprietary and non-profit hospitals;Bays;Social Science and Medicine,1979
5. Regression: Diagnostics Identifying Influential Data and Sources of Collinearity;Belsley,1980