First edition of July, 1945, edited by Mark Van Doren, and subsequent printings should be considered as Number 11 in the Viking Portable Library, *until* the 1974 revision, which was edited by Malcolm Cowley, which was reassigned the Number 78 (in keeping with Viking's indeterminacy principle when it came to assigning series numbers for the Portables). Subsequent Penguin printings after their 1975 acquisition of Viking contain the "078" designation in the ISBN and are also therefore in slot 78 in the VPL. Therefore if your copy is pre-1974, it should be Number 11, while all post-1974 entries should be Number 78.