1. Barker, J. (1999). Singing and music aids to language development and its relevance for children with Down syndrome. Down Syndrome News and Update, 1(3), 133–135. Retrieved March 25, 2006, from http://www.down-syndrome.org/practice/147/ .
2. Bowe, F. G. (2000). Birth to five: Early childhood special education (2nd ed.). New York, NY: Delmar.
3. Bridle, L., & Mann, G. (2000). Mixed feelings: A parental perspective on early intervention. Paper presented at the National Conference of Early Childhood Intervention Australia, Brisbane, June 2000. Retrieved January 24, 2010, from http://www.dsansw.org.au/downloads/Mixed%20Feelings.pdf .
4. Childress, D. C. (2004). Special instruction and natural environments: Best practices in early intervention. Infants and Young Children, 17(2), 162–170.
5. Dmitriev, V. (2001). Early intervention for children with Down syndrome: Time to begin. Austin, Texas: Pro-Ed.