1. Allen, D. A. (1988). Autistic Spectrum Disorders: Clinical presentation in preschool children.Journal of Child Neurology, 3, 548–556.
2. American Psychiatric Association. (1980).Diagnostic and statistical manual of mental disorders (3rd. ed.). Washington, DC: Author.
3. American Psychiatric Association. (1987).Diagnostic and statistical manual of mental disorders (3rd. ed., rev.) Washington, DC: Author.
4. Asperger, H. (1979). Problems of infantile autism.Communication, 13, 45–52.
5. Bayley, N. (1969).Bayley Scales of Infant Development. New York: Psychological Corp.