1. Ainsworth, M. D. S., Bell, S. M., & Stayton, D. J. (1974). Infant-mother attachment and social development: “Socialization” as a product of reciprocal responsiveness to signals. In M. P. M. Richards (Ed.),The integration of a child into a social world (pp. 99–135). London: Cambridge University Press.
2. Alwell, M., Hunt, P., Goetz, L., & Sailor, W. (1989). Teaching generalized communicative behaviors within interrupted behavior chain contexts.Journal of the Association for Persons with Severe Handicaps, 14, 91–100.
3. Bijou, S. W., & Baer, D. M. (1965).Child development 11: Universal stage of infancy. New York, NY: Prentice-Hall.
4. Bowlby, J. (1958). The nature of the child's tie to his mother.International Journal of Psychoanalysis, 39, 350–373.
5. Bowlby, J. (1969).Attachment and loss: Volume 1. Attachment. London: Hogarth Press.