Once more around the UFO controversy, with essentially the same stopovers as those visited in numerous previous saucer books (White, Liss and the Gurneys among juvenile authors). Kettelkamp's review of official studies has the usual implication of a conspiracy of silence, and his catalog of incidents invites belief, though a chapter on ""illusions, pranks and hoaxes"" acknowledges that some have faked saucer sightings and that various visual conditions can simulate the phenomenon. (The photographs here, and throughout the book, are first rate.) Kettelkamp twice suggests that ""some UFO's seen by earth observers may be highly developed mental projections produced by superior beings located elsewhere,"" and ends in a flying logical leap: ""Biologists say that life on other planets is probably based on carbon atoms like life on our planet. For this reason the development elsewhere of beings that we could call humanoids seems likely."" Overall, it's a concise if somewhat weighted summary of saucer lore, well organized and attractively laid out, by a master of far-out subjects; but the need for still another rehash is debatable.