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Zechariah (Sitchin)
– THE STAIRWAY TO HEAVEN., St. Martin’s Press., NY., 1980., pp. 21-23 – Describes Alexander the Great’s journey into the “caverns of the gods“; pp. 52-57 – Refers to ancient Egyptian writings about the subterranean paradise of ‘Seker’, often visited by ancient kings and initiates.
Zirkle, Conway
– THE THEORY OF CONCENTRIC SPHERES., Article in ISIS magazine., Vol. 37, Nos. 109-110., 1947: A discussion of the ‘Symmes Theory‘ of concentric spheres, and the arguments for and against the possibility of a hollow, concavitic earth, and of its interior inhabitants.