best books

hello gents,
I have only been playing hold-em regularly for about a year now. I love the game and have been reading a few books recently, mainly harrington on hold'em. I found these very useful and have definitely improved my game substantially. However i was just wondering what the other books i should think about getting and studying that will improve my hold'em the most are?
i also understand though that there is no substitute for getting on the tables and keep gaining experience, but am eager for any other way to improve my game.
i apologise if this question is better suited to the beginners board.
thankyou for your time.