Correct.Feat from PH. Feat from Martial Heroes Sourcebook. Spell from Arcane Hero Sourcebook. Spell from FR Player's Guide. Magic Item from Adventurer's Vault.
I think you can still end up with player resources from multiple books in 4e.![]()
However, the topic is setting books.

Having that issue with setting books isn't going to happen (unless you mix FR and Eberron and Setting #3 and so on) due to there only being one. For instance, it was frustrating when I was looking for Construct Grafts in two Eberron books, not finding it, only to discover it tucked away in the back of Faiths of Eberron, where it had no topical/organizational sense to be.
And as far as spells (powers, whathaveyou) are concerned, they're much easier to just write down all the pertinent info rather than reference.
On another topic, I'd like to say that more words isn't necessarily better. I never had a whole lot of use for the 3e content, even if there were more words per page or per book. Hell, compare the average page numbers for Prestige Classes versus Paragon Paths (especially those in later 3.5 books that spanned 8 pages). Even if I will never use that PP and have no interest in it, it's 60% of a single page I won't use compared to several pages.