Ernest Volkman is well known for not getting all his facts right. In fact, Jerry Capeci has what he calls the "Volkie Awards," for authors who have screwed up like Volkman has in his books.

That said, even Volkman isn't nearly as bad as Phil Carlo, who is considered a total hack by many.

And, no, there isn't a lot of books on the Genovese. Usually just indirect things in other books. Like the materical on them in Five Families, etc.