Kenneth Bulmer - Of Earth Foretold (1st Digit edition)

Originally published in the U.S. as "The Earth Gods are Coming" as part of an Ace Double with Margaret St. Clair's "The Games of Neith" in 1960. This first U.K. edition from Digit Books (R539) is undated but is circa 1961, and includes an extra novelette "The Aztec Plan". Cover art is not credited.