If one book could cover most topics in general astronomy authoritatively, its Norton. From recommendations on reporting celestial phenomena to specifying telescope characteristics, it seems the author grouped everything that could be of interest to earthbound amateur observers. Very terse in descriptions, Norton's is geared to advanced astronomers who require a reference or a refresher. For example, its star maps are not as clear as a Wil Tirion presentation, but it does not suffer from lack of completeness. For astute beginners, the book is very well indexed and organized, so an unfamiliar concept referred in one section is detailed elsewhere. Readers are rewarded with a book densely packed with information in under two hundred pages.
I was impressed by the care made in the production of the paperbound handbook. Not immediately obvious is that the large page format allow charts and maps to present detail clearly. Tyvec-like bindings allow pages to open flat without distortion. I did not find any typographical errors. The maps, are not ideal for field astronomy use.
Norton's is not light reading, but is encyclopedic in breath and style. For the 20th Edition, its editors should strive for readability, and garner a 5/5 rating.
Marv Gozum, MD