Harrington's HOH books are very good reads for Tourney play. I think that it is a very solid base of knowledge and teach you about core skills needed at the table.
I second Brunson's Super Systems as well. This book is also a great beginner-intermediate level for many poker games
. You should buy it and keep the book as it has TONS of informaiton on other games as well. All of these games come in and out of fashion so it may help to have around incase you want to change up the game you play.
I also recomend Poker Math that Matters by Owen Gains. There may be better poker math books out there but I thought this one was quite good. I think that knowing and getting a better understanding of the mathmatics is a key part of becoming a winning player. Can be a difficult read if not a math person but I think it is well worth getting through to advance you skills.
Theory of Poker by Slansky is also a good one but a little dryer read.
Once beyond that, Elements of Poker is a very good book as by this time if you are still playing you will want to kill all of the donks and will have tilited like crazy from being sucked out on. There is not much hard poker direction in this one but a lot of soft skill information that is helpful to be a good solid player.
For a fun read I recomend Every Hand Reveled by Gus Hansen. Helps get into the mind of a very aggressive poker player... And helps show the post flop skills that a great player like Hansen has developed. A warning after reading this book you may turn into a LAG for bit.. IMO you have to fight that urge
I am sure there are other great books out there but these are the ones that I have read that I thought were worth my time.