1. Agency for Healthcare Research and Quality, 2004. HCUP Overview. Healthcare Cost and Utilization Project (HCUP). See http://www.hcup-us.ahrq.gov/overview.jsp.
2. Agency for Healthcare Research and Quality, 2006a. HCUP Reports. Healthcare Cost and Utilization Project (HCUP). See http://www.hcup-us.ahrq.gov/reports.jsp.
3. Agency for Healthcare Research and Quality, 2006b. HCUP Tools and Software. Healthcare Cost and Utilization Project (HCUP). See http://www.hcup-us.ahrq.gov/tools_software.jsp.
4. Categorical Data Analysis;Agresti,1990
5. An introduction to the Barell body region by nature of injury diagnosis matrix;Barell;Injury Prev.,2002