>Still hoping the older books are relevant.

The older books which are still in publication seem to all be 8.5 or 8.6 and are relevant, I don't recall coming across anything which did not work yet but I am not exactly working through them cover to cover, used them to get the basics and am now using them more as a reference than a guide. Might not be the latest and greatest methods but will get you going. Probably nearing end of life since 9 is in beta, hopefully they will get updated.