Both written by the duo Bill Brewster and Frank Broughton, any "real" DJ that loves the art of spinning records will tell you about these two books.
For everything about learning how to DJ the right way, check out this book that will not only teach you mixing technique but how to run your night:
Every DJ should know its history. Last Night a DJ Saved My Life is the only book that I know of that covers all genres; from Northern Soul to Hip-Hop and how it has evolved until the early 2000's:
These two classics have taught me a ton about the music and art that I love. I hope you enjoy them too.
Play it Cool,