New York: Ace Books, 1963. Illustrated by Roy Krenkel & Frank Frazetta. First Thus. Softcover. Near Fine. Item #H168
Complete & unabridged, cover clean, sharp corners, binding very good, pages clean. "Five hundred miles beneath the surface of the Earth lies another world-- a world of eternal day and endless horizons, in which dinosaurs still roam and cavemen hunt and terrors forgotten in the outer world still survive." ; Cover Art; 6.5" Tall; 221 pages.