1. 1. Beatty, M., McCroskey, J. C., & Valencic, K. (2001). The biology of communic ation: A communication biological perspective. Cresskill, NJ: Hampton
2. 2. Berger, C. R. & Burgoon M. (eds.), (1995). Communication and social influence processes. Michigan State University Press, East Lansing, MI
3. 3. Brophy, J., & Good, T. L. (2000). Looking in classrooms (8th ed.). New York: Harper & Row
4. 4. Burgoon, J. K. (1985). Nonverbal signals. In M. L. Knapp & G. R. Miller (Eds) Handbook of interpersonalcommunication (pp. 344390). Newbury Park, CA: Sage
5. 5. Bush, A. (1977, April). An empirical investigation of teacher clarity. Paper pres ented at the annual meeting of the American Educational Research Association