O'Hair, D., & Friedrich, G. W. (1997). Competent communication (2nd ed.). St. Martin's.
Cita Chicago (17th ed.)O'Hair, Dan, i Gustav W. Friedrich. Competent Communication. 2nd ed. New York: St. Martin's, 1997.
Cita MLA (9th ed.)O'Hair, Dan, i Gustav W. Friedrich. Competent Communication. 2nd ed. St. Martin's, 1997.
Atenció: Aquestes cites poden no estar 100% correctes.