Books and ebooks I recommend to deepen your music theory knowledge.
Elements Of The Jazz Language
I learned a lot from this book! True to its title it feels like a dictionary of commonly used music elements. Although it talks about the “Jazz Language”, it really applies to other genres like pop or rock music as well. Every seasoned improviser and songwriter should know the 3-b9 resolution, the bebop lick or the back door progression.
This book gives a musician a great arsenal of music elements to “speak” with while composing or improvising.
A wonderful book for beginner and advanced reharmonizers. It explains various song reharmonization techniques – starting with simple substitutions and the diatonic approach and getting into more advanced music theory topics like modal interchange, modal reharmonization or diminished seventh chords.
I draw from this book a lot when I do my song reharmonizations on YouTube! It is well written and clearly structured, which helps to practice each of the reharmonization techniques separately.
The Real Book Play-Along: Volume 1 Sixth Edition
Every serious musician should own a copy of The Real Book! It contains hundreds of songs considered “standards” across the music world. This edition even comes with play-along tracks (thankfully they include USB and I believe a download link nowadays).
Though the Real Book focuses on jazz, it is a helpful study tool for all genres. I use it to practice reharmonization techniques and to try out solo and improvising techniques.
If you prefer rock songs to practice with, I can recommend The Real Rock Book (volume 2) I also own.