Verderber, R. F. (1979). The challenge of effective speaking (4th ed.). Wadsworth Pub. Co..
Cita Chicago (17th ed.)Verderber, Rudolph F. The Challenge of Effective Speaking. 4th ed. Belmont, Calif.: Wadsworth Pub. Co., 1979.
Cita MLA (9th ed.)Verderber, Rudolph F. The Challenge of Effective Speaking. 4th ed. Wadsworth Pub. Co., 1979.
Atenció: Aquestes cites poden no estar 100% correctes.