AusubelD. D. (1968). Educational psychology: A cognitive view. New York: Holt, Rinehart & Winston, Inc.
2.
BensbergG. L. (1953). The relation of academic achievement of mental defectives to mental age, sex, institutionalization and etiology. American Journal of Mental Deficiency, 58, 327–330.
3.
BlakeK. A. & WilliamsC. L. (1968). Induction and deduction and retarded, normal and superior subjects’ concept attainment. American Journal of Mental Deficiency, 73, 226–231.
4.
BrunerJ. S. (1964). The course of cognitive growth. American Psychologist, 19, 1–15.
5.
BurnsP. C. (1961). Arithmetic fundamentals for the educable mentally retarded. American Journal of Mental Deficiency, 63, 57–61.
6.
CawleyJ. F. & GoodmanJ. O. (1969). Arithmetic problem solving: A program demonstrated by teachers of the mentally handicapped. Exceptional Children, 36, 83–88.
7.
CawleyJ. F. & VitelloS. J. (1972). Model for arithmetical programming for handicapped children. Exceptional Children, 39, 101–110.
8.
CruickshankW. M. (1948). Arithmetic ability of mentally retarded children: Ability to differentiate extraneous material from needed arithmetic facts. Journal of Educational Research, 42, 161–170.
9.
DunnL. M. (1954). A comparison of the reading processes of mentally retarded and normal boys of the same mental age. Monograph of the Society for Research in Child Development, 19(1, Serial No. 58).
10.
ElkindD. (1961). The development of quantitative thinking: A systematic replication of Piaget's studies. Journal of Genetic Psychology, 98, 36–46.
11.
FehrH. F. (1966). The teaching of mathematics in the elementary school. In KlausmeierH. J. & HarrisC. W. (Eds.), Analyses of concept learning. New York: Academic Press.
12.
GagneR. M. (1970). Conditions of learning. New York: Holt, Rinehart & Winston, Inc.
13.
GoldsteinH., MossJ., & JordanL. (1965). The efficacy of special class training on the development of mentally retarded children. Cooperative Research Project No. 619, University of Illinois.
14.
HoodH. (1962). An experimental study of Piaget's theory of development of numbers in children. British Journal of Psychology, 53, 273–286.
15.
IanoR. D. (1971). Learning deficiency versus developmental conceptions of mental retardation. Exceptional Children, 38(4), 301–310.
16.
InhelderB. (1968). The diagnosis of reasoning in the mentally retarded. New York: John Day Co.
17.
JensenA. R. (1971). A theory of primary and secondary familial mental retardation. In EllisN. R. (Ed.), International review of research in mental retardation (Vol. 4). New York: Academic Press.
18.
KermW. A. (1967). Negative transfer in sorting tasks, MA and IQ in normal and retarded children. American Journal of Mental Deficiency, 72, 416–421.
19.
KirkS. A. (1964). Research in education. In StevensH. A. & HeberR. (Eds.), Mental retardation: A review of research. Chicago: University of Chicago.
20.
KolstoeO. P. (1972). Mental retardation: An educational viewpoint. Holt, Rinehart & Winston, Inc.
21.
KouninJ. S. (1941). Experimental studies of rigidity: I. Measurement of rigidity in normal and feeble-minded persons. Characteristics and Personality, 9, 251–273.
22.
LovellK. (1971). The growth of basic mathematical and scientific concepts in children. London: University of London Press, Ltd.
23.
LovellK., MitchellB., & EverettI. R. (1962). An experimental study of the growth of some logical structures. British Journal of Psychology, 53(2), 175–188.
24.
MilgramN. A. (1966). Verbalization and conceptual central classification in trainable mentally retarded children. American Journal of Mental Deficiency, 70, 763–765.
25.
NoffsingerT. & DobbsV. (1970). Teaching arithmetic to educable mentally retarded children (review). Journal of Educational Research, 64(4), 177–184.
26.
PiagetJ. (1970). The stages of the intellectual development of the child. In KramerK. (Ed.), Problems in the teaching of elementary school mathematics. Boston: Allyn and Bacon.
27.
QuayL. C. (1963). Academic Skills. In EllisN. R. (Ed.), Handbook of Mental Deficiency. New York: McGraw-Hill.
28.
RobinsonH. B. & RobinsonN. M. (1965). The mentally retarded child: A psychological approach. New York: McGraw-Hill.
29.
StephensW. B. (1971, April). A Piagetian approach to arithmetic for the mentally retarded. Paper presented at International Meeting of the Council for Exceptional Children, Miami.
30.
StephensW. E. (1966). Category usage of normal and subnormal children in three types of categories. American Journal of Mental Deficiency, 71, 266–273.
31.
Van EngenH. & StiffeL. D. (1966). First grade children's concept of addition of natural numbers. Research and Development Center for Learning and Re-education, University of Wisconsin, Madison, Wisconsin.
32.
VitelloS. J. (1973). An attempt to facilitate class inclusion among retarded children. American Journal of Mental Deficiency, 78(2), 158–162.
33.
WoodwardM. (1961). Concepts of number of the mentally subnormal divided by Piaget's method. Journal of Child Psychology and Psychiatry, 2, 249–259.