OldnDecrepit;34711 wroteSecondly, I've found them difficult to use in that finding the right part for YOUR model is a bit tedious. Sometimes there are so many variations over the years that identifying the part is tricky. It may be easier for those with a mechanical background and it does get easier over time.
I use VADIS for parts & the green books for everything else (technical description, repairs, removal & installation instructions etc). VADIS is a lot easier to use when looking up parts as you start by selecting year model, engine & transmission type, then it only shows you what's relevant & hides everything else. Another advantage of VADIS is that you can do a full install & run it purely off your hard drive so you don't need to insert DVD every time you use it. VADIS contains some of the information from the green books as well but not as complete.
Message me if you want a copy of VADIS.