My wife has a keen eye when it comes to misspellings, typos and such. She constantly finds them in newspapers, magazines, and perhaps most often in restaurant menus. Some of them can be fairly amusing. To get an author's name wrong on the cover of a book, however, doesn't seem amusing. You have to wonder how many copies were printed with that error. This printing is the 4th, dated 1970. Perhaps this error is well-known to collectors of the series.
Who knows, there may be a plethora of misspellings out there. Maybe I should be looking for The Nymph and the Lamb by Thomas H. Raddall, Birney by Earle Turvey, As For Me and My Mouse by Sinclair Ross, or Such is My Beloved by Morbid Callaghan. I sort of like that last one.