Wilding-White T. Usborne World of the Unknown: Ufo\'s. - Tulsa, OK : Edc Pub, 1989. - 32 p. : ill. (mostly col.) 8.75 x 11 x 0.25 inches - Usborne world of the unknown . The World of the Unknown series explores the frontiers between belief and fact. ISBN: 0860201503 Subjects--Topical Terms: Unidentified flying objects.Science fictionUFO's