APA (7th ed.) Zitazioa
Carkhuff, R. R. (2009). The art of helping (9th ed.). HRD Press.
Chicago Style (17th ed.) Zitazioa
Carkhuff, Robert R. The Art of Helping. 9th ed. Amherst, Mass.: HRD Press, 2009.
MLA (9th ed.) Zitazioa
Carkhuff, Robert R. The Art of Helping. 9th ed. HRD Press, 2009.
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