The seventeen volumes of the 'Collected Works' of Sigmund Freud, the most comprehensive edition of his oeuvre in the original language to date, were first published between 1940 and 1952 by Freud's London exile publisher, before being taken over by S. Fischer in 1960. However, for various reasons, important pieces of the psychological-psychoanalytic work were missing. Some examples include: the contributions of Josef Breuer to the 'Studies on Hysteria' (at Freud's own request); the early 'Draft of a Psychology' (initially published posthumously as part of the letters to Fliess); the insightful notes from the treatment of the patient known as the "Rat Man" (first uncovered in the 1950s); and the draft of the twelfth metapsychological essay, discovered only in 1983. This and many other pieces, especially from the pioneering period of psychoanalysis, are collected in this extensive editorial work.