1. Sullivan, H. S.: Interpersonal Theory of Psychiatry, W. W. Norton, New York, 1955.
2. Abell, Richard G.: Personality Development During Group Psychotherapy; Its Relation to the Etiology and Treatment of the Neuroses, Amer. J. Psychoan., 1959, 20, 53.
3. Rogers, Carl R.: The Process Equation of Psychotherapy, Lecture sponsored by the Guidance and Counseling Alumni of San Francisco State College, San Francisco, June 17, 1959.
4. Rogers, Carl R. and Richard A. Rablen: A Scale of Process in Psychotherapy, University of Wisconsin, 1958.