The sad news is all of these campground "books" don't list every campground in the country, just the ones that have contacted the publisher or the publisher has contacted them. The camp club membership ones are even more limited to places that give their discounts.
We use our Woodalls because the listings do show what size rig will fit in their spaces but we also take notes when traveling so we have a better idea of what is available that is not listed in any book. We also belong to Passport America. We found PA has very few campgrounds in areas we are likely to visit. Only twice in 10 years has it been helpful whereas Woodalls has been very handy.
For example...in the state of Nebraska many of the small towns have donation fee sites and limited boondocking in their city parks. There is a 4 site RV park in the town 4 miles from us but they do not list/advertise in any RV book. So, there are places out there but it is sometimes hard to find them.