Lyle Gifford Boyd, The World of Flying Saucers: A Scientific Examination of a Major Myth of the Space Age (1963)
“ In military parlance the phrase “unidentified flying object,” abbreviated as UFO, is used to indicate any air-borne phenomenon that fails to identify itself to, or to be identified by, trained witnesses on the ground or in the air who are using visual or radar methods of observation. Created in the early days of the saucer era, the term UFO is unfortunately misleading because it seems to imply that the unknown is a solid material object. ”
