The 13th Immortal / This Fortress World
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Overview:
- Title: The 13th Immortal / This Fortress World
- Author: Robert Silverberg James E. Gunn
- Year: 1957
- Type: Omnibuses
Editions/Publications:
- Unknown. The 13th Immortal / This Fortress World (Unknown, Robert Silverberg, Ace Books, $0.35, 129+190 pages, dos, Omnibus)
- Unknown. The 13th Immortal / This Fortress World (Unknown, James E. Gunn, Ace Books, $0.35, 129+190 pages, dos, Omnibus)