Edward Ruppelt was a United States air Force officer. While working on a government study called Project Blue Book, he coined the term unidentified flying object. This term replaced the words flying saucer. The period when Ruppelt was with Project Blue Book was the time the best investigations into UFO's were completed. The Report on Unidentified Flying Objects was published after Ruppelt left Project Blue Book. The book is notable because it was, for several decades, the only account of Air Force UFO studies written by a participant. This book is essential for anyone interested in the history of the UFO sitings. Ruppelt discusses his time with Projects Grudge and Blue Book. His assessments of some UFO cases, including a portion he thought were puzzling and unexplained is a fascinating account of the period and the thinking of the man at the center of the investigations. . Ruppelt also reveals much insider material.