Soft cover. Condizione: Near Fine. "Mutant human beings learn to penetrate the dimensions of spacetime and find a 'ring' of pristine alternative Earths. . very enjoyable . The best of Simak's early novels." -- The Ultimate Guide to Science Fiction. Mass market paperback. Publisher book number V2317, cover price $0.75. This is a used book. Pages are clean and bright with no markings, notes, or highlighting. Cover shows only minor shelf wear and is not creased. No owner's marks or bookplates, not ex-library. Binding is tight and square. Corners not bumped. An excellent reading copy.