Next Poker book for me to get?

I have read the two Harrington books, Hellmuth's Play Poker Like the Pros, Gary Carson's Hold Em Poker book, as well as Super System. Any suggestions for my next title? Ciaffone, Skylansky, Super System II?

I play small stakes no limit hold'em on Poker Stars as well as seven card stud and omaha occasionally.

I am very interested in Omaha Hi/Lo but don't understand the game too well (read Hellmuth's take).

Any thoughts?