1. American Psychiatric Association (1987)DSM-III-Revised: Diagnostic and statistical manual of mental disorders. Revised Edition. Washington, D.C.: The Association.
2. Bowlby, J. (1953)Child care and the growth of love, Baltimore: Penguin Books.
3. Bowlby, J. (1967)Attachment and loss: Volume I, New York: Basic Books.
4. Casey, K., McGee, J.J., Stark, J. & Menolascino, F.J. (1985)A Community-Based Service System for the Mentally Retarded: The ENCOR Experience. Lincoln: University of Nebraska Press.
5. Cicchetti, D., & Serafica, F.C. (1981) Interplay among behavioral systems: Illustrations from the study of attachment, affiliation, and wariness in young children with Down's syndrome.Developmental Psychology, 17, 36?49.