Brekke, B., Williams, J.D., & Tait, P.The acquisition of conservation of weight by the visually impaired . Journal of Genetic Psychology, 1974, 125, 89-97.
2.
Elkind, D.Children's discovery of the conservation of mass, weight, and volume: Piaget replication study II. Journal of Genetic Psychology , 1961, 98, 219-227.
3.
Furth, H. G. Conservation of weight in deaf and hearing children. Child Development, 1964, 35, 143-150.
4.
Melcer, J.D.Sensory-motor experience and concept formation in early childhood . (Doctoral dissertation, University of Texas.) Ann Arbor, Mich. : University Microfilms, 1966 , No. 67-3330.
5.
Miller, C.K.Conservation in blind children. Education of the Visually Handicapped. 1969, 1(4), 101-108.
Tessier, F.A.The development of young cerebral palsied children according to Piaget's sensorimotor theory. (Doctoral dissertation, University of California , Los Angeles.) Ann Arbor, Mich. : University Microfilms, 1969, No. 70-8213.
8.
Williams, J. D., & Lindem, A.C.Analysis of covariance with multiple covariates (CO-VARMLT). Educational and Psychological Measurement, 1972, 32, 815-816.