Walborn, F. S. (1996). Process variables: Four common elements of counselling and psychotherapy. Brooks/Colege Pub.
Lua i Stíl Chicago (17ú heag.)Walborn, Frederick S. Process Variables: Four Common Elements of Counselling and Psychotherapy. Pacific Grove, Calif: Brooks/Colege Pub, 1996.
Lua MLA (9ú heag.)Walborn, Frederick S. Process Variables: Four Common Elements of Counselling and Psychotherapy. Brooks/Colege Pub, 1996.
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