1. Information and codification: A philosophical approach;Bateson,1951
2. Toward a theory of play and fantasy;Bateson,1972
3. Fein, G. The social competence of play. Paper presented at the annual meeting of the American Education Research Association, San Francisco, April 1976.
4. Garvey, C., & Berndt, R. The organization of pretend play. Paper presented at the annual meeting of the American Psychological Association, Chicago, August 1975.
5. The discovery of grounded theory;Glaser,1967