Carkhuff, R. R. (1983). The art of helping (5th ed.). Human Resource Development Press.
Cita Chicago (17th ed.)Carkhuff, Robert R. The Art of Helping. 5th ed. Amherst, Massachuttes: Human Resource Development Press, 1983.
Cita MLA (9th ed.)Carkhuff, Robert R. The Art of Helping. 5th ed. Human Resource Development Press, 1983.
Atenció: Aquestes cites poden no estar 100% correctes.