1. Bernhardt, M., & Mackler, B. (1975). The use of play therapy with the mentally retarded.Journal of Special Education, 9(4), 409–414.
2. Saracho, O.N. (1984). Construction and validation of the Play Rating Scale.Early Child Development and Care, 17, 199–230.
3. Spodek, B. (1985).Teaching in the early years (3rd ed.). Englewood Cliffs, NJ: Prentice-Hall.
4. Spodek, B., Saracho, O.N., & Lee, R.C. (1984).Mainstreaming young children. Belmont, CA: Wadsworth.
5. Strain, P.S., Cooke, T.P., & Apolloni, T. (1976).Teaching exceptional children: Assessing and modifying social behavior. New York: Charles C. Thomas.