ace books mmpb first printing, first merkin edition, first p/b edition
ace science fiction special (first series)
cover art by diane dillon, leo dillon (as by leo & diane dillon)
cover price 60¢
192pp. including titles, indica etc, end pp. advertising
bears both letter price code prefix cat# (on front cover) and five-digit system cat# (on spine),
the latter prefixed with a non-isbn publisher I'd code, 020, which may be part of the abn system (this comment is from another edition of this book)