Freud, Sigmund (1923). Das Ich und das Es (in German). Leipzig, Vienna, and Zurich: Internationaler Psycho-analytischer Verlag. English translation, The Ego and the Id. Translated by Riviere, Joan. London, UK: Hogarth Press and Institute of Psycho-analysis. 1927. Revised for Strachey, James, ed. (1961). The Standard Edition of the Complete Psychological Works of Sigmund Freud. New York, NY: W.W. Norton and Company.