1. The World Health Organization International Classification of Functioning http://www.who.int/classifications/icf/en/
2. U.S. Department of Commerce, Economics and Statistics Administration, U.S. Census Bureau Census 2000 Brief
3. U.S. Department of Commerce, Economics and Statistics Administration. U.S. Census Bureau Americans With Disabilities: 2005
4. Centers for Disease Control National Health Interview Survey http://www.cdc.gov/nchs/nhis/nhis_products.htm
5. Center for Disease Control Autism Spectrum Disorders (ASDs): Data and Statistics http://www.cdc.gov/ncbddd/autism/data.html/