The RKMs are an amazing resoruce. Yes it's old, but the amount and quality of information is excellent and the majority is applicable to modern systems.
I'm fortunate in that my university has a complete set in the reference library that I look at quite often. It really is best to read it in book form. I have the AmigaGuide versions present on the 3.5 NDK, and frankly they're not a patch on having the real book. :-(