I think that anyone who's truly interested in the subject of alien visitation (invasion) would do well to start with these 3 toobs and Don's wonderful little book. I first read this book when I was about 15 and it sparked a lifelong interest in all things wondrous and highly strange. Before there was a Richard Dolan aggregating thousands of reliable sightings in an historical and cohesive series of books there was Donald Keyhoe doing the very same thing but preceding Rich by 50 years. He wrote during the time when the vale of secrecy was first being imposed by Air Force, Naval and Army intelligence. During the time of the famous (or infamous) Robertson CIA Commission Report and during the time of the institutionalization of secrecy under the direction of President Truman (using methods just recently acquired by the successfully black Manhattan Project that resulted in the creation of the atomic bombs dropped on Japan 5 years before publication of his book.) America in those days not only knew how establish and maintain secret programs but in fact had raised the methodology involved to a science- a science that oppresses us to this day.