6Cox, L. Analysis, classification, and frequency of systematic error computational patterns in the addition, subtraction,multiplication, and division vertical algorithms for grades 2-6 and special education classes. Technical report ED 092 407,Kansas University Medical Center, Kansas City, KA, 1974.
7Buswell, G.T, Diagnostic Studies in Arithmetic. Chicago, IL: University of Chicago Press, 1926.
8Ainsworth, S. A model of children's multiplication skills. Unpublished project, Portsmouth Polytechnic, UK, 1991.
9Dallaway, R.Z. Dynamics of Arithmetic: A Connectionist View of Arithmetic Skills. CSRP 306, Univerity of Sussex,Brighton, 1994.
10Semenza, C, Miceli, L, Girelli, L. A deficit for arithmetical procedures: lack of knowledge or lack of monitoring? Cortex, 1997, 33(3): 483-498.
