Book Review: 'UFO'

Computer fanatics and UFO true believers tend to have similar glints in their eyes, so this compendium of more than 1,200 ''documented sightings,'' 202 pie-plate photographs, and 22 grainy movie enlargements will probably find a lot of takers in multimedia-land. It's a weird yet admirably thorough reference disk, which lets you locate incidents under such headings as ''abduction,'' ''psychic phenomena,''and ''cattle mutilation.'' Pictures, too. Yum. B