There are well over 200 poker book titles out there.
A lot of good stuff but also a lot of cheap crap!
I would focus on the top 7 listed below, but it all depends on the type of games you play!
1 - Applications of NLHE (Matthew Janda)
2 - No-Limit Hold 'em For Advanced Players (Matthew Janda)
3 - Modern Poker Theory (Michael Acevedo)
4 - Fundamental No-Limit Hold'em Mathematics You Need (Alton Hardin)
5 - The Mental Game of Poker (Jared Tendler)
6 - Zachary Elwood - Reading Poker
tells.PDF
7 - Professional No Limit (Flynn-Mehta-Miller)
Good luck at the tables!