What book is best for sngs?

[brizzypare]

I'm looking into buying a book that will help refine my NL hold 'em play. I play hold 'em exclusively (i.e. no stud, etc.), and lately I've begun playing only sng's, where I'm doing fairly well.

But I'm sure I can do better. I know TOP and HEFAP are top on everyone's list as far as hold 'em goes, but will they be very helpful with no limit SNG's, or do they deal mostly with limit? I know Harrington has a new book out; how helpful would his book be? There are probably oodles of books out there that I've never heard of that are infinitely helpful, so if anyone out there could give me some suggestions as to the best book (or books) that can help me improve and refine my no limit SNG play, that would be very helpful. Thanks in advance.