1. Bozzo, M. T., & Zecca, G. M. (1993). Adattamento italiano della Scala d’intelligenza Stanford-Binet forma L-M nella revisione Terman-Merrill. Firenze: Organizzazioni Speciali.
2. Relations among maternal stress, cognitive development, and early intervention in middle- and low-SES infants with developmental disabilities;Brinker;American Journal on Mental Retardation,1994
3. Brown, R. (1973). Language development: The early stages. Cambridge: Harvard University Press.
4. Early vocabulary acquisition by children with Down syndrome;Cardoso-Martins;American Journal of Mental Deficiency,1985
5. Language skills of children and adolescents with Down syndrome;Chapman;Journal of Speech, Language and Hearing Research,1998