This is a vintage original hardback edition second printing (revised 1988) of MYSTERIES OF THE UNKNOWN: THE UFO PHENOMENON. Published in 1987 by Time-Life Books, this volume discusses sightings and controversies regarding unidentified flying objects. Topics include alien encounters, the Roswell incident, and allegations of government cover-ups. This 9.25 x 11.25 in. hardback book consists of 160 pages with great black-and-white and full-color photographs and illustrations. It is in "Like New" condition with some areas of light rubbing on the artwork on the front cover. Mysteries of the Unknown is a 33-volume series of books about the paranormal, published by Time-Life Books from 1987 through 1991. Each book focused on a different topic, such as ghosts, UFOs, psychic powers, and dreams. The series was very successful for Time-Life Books, and the idea was conceived following the popularity of the publisher's previous Enchanted World series of books. However, unlike the definite supernatural orientation of The Enchanted World series, the Mysteries Of The Unknown series did all it could to keep its subject matter as grounded in scientific aspects as was possible for the subject. Within 15 months of the series' release, it had broken every sales record for the company.