1. Angoff, W. (1984). Scales, norms, and equivalent scores Princeton, NJ: Educational Testing Service.
2. Bayley, N. (1969). Bay ley scales of infant development New York: The Psychological Corp.
3. Buckley, L. (1984). Cardiac assessments. In S. Pueschel (Ed.), The young child with Down syndrome (pp. 351–664). New York: Human Sciences Press.
4. Carr, J. (1970). Mental and motor development in young Mongol children. Journal of Mental Deficiency Research, 14 (31), 205–220.
5. Carr, J. (1975). Young children with Down’s syndrome London: Butterworths.