1. American Psychiatric Association. (1994). Diagnostic and statistics manual of mental disorders (DSM-IV) (4th ed.). Washington, DC: American Psychiatric Association.
2. Baird, G., Simonoff, E., Pickles, A., Chandler, S., Loucas, T., Meldrum, D., et al. (2006). Prevalence of disorders of the autism spectrum in a population cohort of children in South Thames: The Special Needs and Autism Project (SNAP). Lancet, 368, 210–215.
3. Bentler, P. M. (1990). Comparative fit indexes in structural models. Psychological Bulletin, 107, 238–246.
4. Berument, S. K., Rutter, M., Lord, C., Pickles, A., & Bailey, A. (1999). Autism screening questionnaire: Diagnostic validity. British Journal of Psychiatry, 175, 444–451.
5. Bodfish, J. W., Crawford, T. W., Powell, S. B., Parker, D. E., Golden, R. N., & Lewis, M. H. (1995). Compulsions in adults with mental-retardation—Prevalence, phenomenology, and comorbidity with stereotypy and self-injury. American Journal on Mental Retardation, 100, 183–192.