Routledge is now re-issuing this prestigious series of 204 volumes originally published between 1910 and 1965. The titles include works by key figures such asC.G. Jung, Sigmund Freud, Jean Piaget, Otto Rank, James Hillman, Erich Fromm, Karen Horney and Susan Isaacs. Each volume is available on its own, as part of a themed mini-set, or as part of a specially-priced 204-volume set. A brochure listing each title in the International Library of Psychology series is available upon request.

Wolfgang Koehler demonstrated that chimpanzees could solve problems by applying insight. His research showed that the intellectual gap between humans and chimpanzees was much narrower than previously thought. The work was revolutionary when originally published in 1917 in German, but it was largely ignored for decades because it violated the conventional wisdom that animal behavior is simply the result of instinct or conditioning.