There are a more books on karate than I care to think about. There are a number that I would recommend.
For general Shotokan Karate for Kyu grade students, you can not go wrong with M Nakayama’s Best Karate Series 1 - 11
Or M Nakayama’s Dynamic Karate
For the advanced student of karate I would recommend four books by Iain Abernethy
Bunkai Jutsu
Arm-locks for all styles
Throws for strikers
Karate’s grappling methods