There really is an encyclopedia where you can search by the initial letter to people, places, organizations or equipment that occurred in the series. In this Gary Russell goes very in depth, in which he performs for example nearly every supporting character, which was described in an episode by name.
What makes the book extremely interesting are the many pictures in great quality, some of which were even printed on single pages. I want the written content is not small talk, but the images alone were worth the purchase.
Who as a fan of the series examined this kind of supplement to his favorite series, which is in good hands with this book.