There seems to be 2 versions of the original novel with differing covers. The first version is a full photo and the second uses the same photo but with a green border. The second one seems to be more common to find so I would assume it was published quite soon after the first one, however it is the first one that I remember as my brother got it in the late 70s. When would the second version have appeared?
In my small collection are both versions. The first one was published in 1970. The second one (green border) in 1986. On page four of this book there is a list of all the prints and reprints. It says: first published in 1970, reprinted 1970, 1971 (twice), 1973, 1975 (twice), 1976 (twice), 1979, 1980 (twice), 1981, 1983, 1984, 1986. The question now is when the green version was published for the first time. My green version is from 1986. It could also be one of the reprints from the early 80s. Hope this information is useful.