Woolman, M., & Davy, R. A. (1963). Developing symbolic skills in the mentally retarded. s. n.
Dyfyniad Arddull ChicagoWoolman, Myron, and Ruth Ann Davy. Developing Symbolic Skills in the Mentally Retarded. Washington, D. C: s. n, 1963.
Dyfyniad MLAWoolman, Myron, and Ruth Ann Davy. Developing Symbolic Skills in the Mentally Retarded. s. n, 1963.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.