The Crossroads of Time / Mankind on the Run

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Overview:

Title: The Crossroads of Time / Mankind on the Run
Author: Gordon R. Dickson Andre Norton
Year: 1956
Type: Omnibuses

Editions/Publications:

Unknown. The Crossroads of Time / Mankind on the Run (Unknown, Gordon R. Dickson, Ace Books, $0.35, 169+151 pages, dos, Omnibus)
Unknown. The Crossroads of Time / Mankind on the Run (Unknown, Andre Norton, Ace Books, $0.35, 169+151 pages, dos, Omnibus)