Ace Special Editions
(Scans and commentary are by Kenneth R. Johnson)
These were re-issues of books that had been previously issued by Ace as halves of Double Novels, with the same book numbers. These 4 variant editions have been well documented within the SF field and are mentioned in both Hancer's and Holroyd's price guides. These editions are undated; the only thing that is certain is that they must have been issued before 1961 when the first one (the Leinster) was re-issued with a new number. They were never advertised in any of the other Ace SF books which suggests that they were produced for some alternate form of distribution; my suspicion is that they were produced for the Teen-Age Book Club for distribution through schools. All four would have been perfect fare for the young adult market, which most of Ace's mysteries and westerns were not.
(And here's a comment by Bob Weinberg, an avid collector and seller of Science Fiction books and artwork.)
I'm writing about the four
Ace Special paperbacks mentioned on your site published for 25 cents each back
in the late 1950's. I can say for a certainty that these were done for the
Teenage Book Club (TAB) as I was in grade school when these books were offered
for sale in the monthly TAB newsletter. I bought them all, at a quarter each,
and remember them quite well. I bought them when I was in fifth grade, which
would be 1957. They are the books that started me collecting science fiction.