1. http://www.census.gov/
2. International Classification of Diseases. 9th revision. Clinical modification. 6th Edition. 2003
3. Design and operation of the National Hospital Discharge Survey;Vital Health Stat [1],2000
4. National Hospital Discharge Survey, 2001. Public use data file documentation. Atlanta (GA): US Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Health Statistics, Division of Health Care Statistics (NHDS@cdc.gov)
5. Hall MJ, Owings MF. 2000 National Hospital Discharge Survey. Advance data from vitaland health statistics, no. 329. Hyattsville (Md): National Center for Health Statistics; 2002. Available from: URL: http://www.cdc.gov/nchs/products/pubs/pubd/ad/321-330/ad329.htm