Encyclopedia of Clinical Psychology
Available online, or as a 5-volume print set, The Encyclopedia of Clinical Psychology includes well over 500 A-Z entries covering the main topics, key concepts, and influential figures in this field.
Cautin, R. L., & Lilienfeld, S. O. (Eds.) (2015). Encyclopedia of clinical psychology. Chichester, West Sussex; Malden, MA: John Wiley and Sons.