6M ahoney G, Finger I, Powell A. Relationships of mater- nal behavioural style to the development of organically impaired mentally retarded in fants. American Journal of Mental Deficiency,2011,90:296 - 302.
7Stoel- Gammon C. Down Syndrome phonology: Devel- opmental patterns and intervention strategies. Down Syndrome Research and practice, 2001,7 (3) : 93 - 100.
8Buckhalt J A, Rutherford R B, Goldberg K E. Verbal and nonverbal interaction of mothers with their Down Syndrome and nonretarded infants. American Journal of Mental Deficiency, 1998,82(4) : 337 - 343.
9Carvajal E, Lglesias J. Looking behavior and smiling in Down Syndrome infants. Journal of Nonverbal Commu- nication,2000, 24(3) : 225 - 236.
10Jeffrey B C, Lacono T. Gesture and word production in children with Down Syndrome. Autgnentative & Alternative Communication,2001,17(2) : 73 - 87.