Probably the easiest, fastest, and least expensive "guide" for campgrounds, is to just do an internet search by typing in the name of the city, town, or location followed by the word, "Campground", and you'll get pretty much everything in that area listed.
For example, Nashville, Tennessee, campground. You'll get hits on local, private, county, state, and federal campgrounds in that area.
And remember, every state has a DNR (Department of Natural Resources) that lists the State campgrounds too, and links to make reservations.
Don't underestimate the KOA.com web site for searching for KOA campgrounds, and GoodSam has a pretty decent campground search feature too.
The internet is going to be more current, more relevant, and give you the ability to make reservations on-line...much easier than dragging around outdated books.