New York: Ace Books, . First Separate Edition. Paperback. The second American paperback edition, & the first separate edition. Small octavo, original pictorial wrappers. Issued as Ace 86608 (75¢). Off-white paper. Minor tanning to inside of covers, very small ink "squiggle" on inner front cover, small scuff on rear cover; a very good to near-fine copy. Near Fine. Item #311454
¶ Originally issued in 1960 as Ace D-457 backed with THE SKYNAPPERS by John Brunner.