I've got several, but find that 'Electrical Wiring: Residential' by Ray C. Mullin is the one I most commonly reach for when I have a question (and my boss isn't nearby to answer or I'm not at my computer to check here). That book, paired with a copy of the Code, has been an immense help. Most of the stuff at the home centers is more DIY oriented and from what I've seen doesn't get in-depth enough where necessary and none of them that I've come across at such places have been any help in learning how to navigate the Code...
In fairness, I haven't checked out Mike Holt's available material yet (other than what's on the site), but from what others have said about it, it's probably among the best.