Knapp, M. L., & Hall, J. A. (1997). Nonverbal communication in human interaction (4th ed.). Harcourt Brace College Publishers.

Knapp, Mark L., and Judith A. Hall. Nonverbal Communication in Human Interaction. 4th ed. Fort Worth: Harcourt Brace College Publishers, 1997.

Knapp, Mark L., and Judith A. Hall. Nonverbal Communication in Human Interaction. 4th ed. Harcourt Brace College Publishers, 1997.