1. National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention Atlanta Georgia USA
2. Department of Epidemiology Boston University Boston Massachusetts USA
3. Department of Epidemiology University of North Carolina Chapel Hill North Carolina USA
4. Anschutz Medical Campus University of Colorado Boulder Colorado USA
5. School of Public Health, Georgia State University Atlanta Georgia USA
6. Institute for Disabilities University of Wyoming Laramie Wyoming USA
7. The Autism Research Program, Kaiser Permanente Northern California Oakland California USA
8. Center for Autism Research, Children's Hospital of Philadelphia Philadelphia Pennsylvania USA