New York: Ace Books, Inc., 1961. Ed Emshwiller and Ed Valigursky. First edition, first printing. Paperback. Item #45126
Ace Double, book number F-123. Cover price 40¢. Covers illustrated by Ed Emshwiller and Ed Valigursky. Long thin raised line to the Brackett title. Barely perceptable. A very good plus copy.