Cita APA (7a ed.)

Hill, C. E., & O'Brien, K. M. (1999). Helping Skills: : faciliting exploration, insight, and action (4th print. of the 1st ed.). American Psychological Association.

Cita Chicago Style (17a ed.)

Hill, Clara E., y Karen M. O'Brien. Helping Skills: : Faciliting Exploration, Insight, and Action. 4th print. of the 1st ed. Washington: American Psychological Association, 1999.

Cita MLA (9a ed.)

Hill, Clara E., y Karen M. O'Brien. Helping Skills: : Faciliting Exploration, Insight, and Action. 4th print. of the 1st ed. American Psychological Association, 1999.