New York, New York: Ace Books, 1957. Ed Emshwiller; Ed Valigursky. 1st Edition. Soft cover. Very good paperback copy of "The 13th Immortal" by Robert Silverberg and "The Fortress World" by James E. Gunn. 1st edition / 1st Ace Double Novel Books printing D-223 with a cover price of 35..... More