OUR ANCESTORS CAME FROM OUTER SPACE by Maurice Chatelain

Chatelain uses astrology and pyramid power to prove OUR ANCESTORS CAME FROM OUTER SPACE! Our ex-NASA author also marshals prehistoric polar shifts, the Maltese Cross, and a host of other numerological jibber jabber including the now-ubiquitous Mayan Calendar to fill out his argument. Available to read and download at archive dot org.

Dell Publishing, 1979 (original pub. 1974)

INCIDENT AT EXETER by John G. Fuller

Hard boiled journalism meets the UFO. Unlike Fuller's other UFO subject (The Interrupted Journey of Betty and Barney Hill) the eponymous Exeter incident hasn't persisted into modern Ufology's zeitgeist, though some researchers have commented on Fuller's intelligence connections and the possibility that the prolific author was running cover for more earthly operations. 

A Berkeley Medallion Book, 1966