
Also, not a theory book but the most important music learning book I've read: The Perfect Wrong Note [1]. Reading this permanently changed the way I approach learning the piano (or synth. in my case) and I my playing has vastly improved over the last couple of years because of it.
[0] https://rowman.com/ISBN/9780810862333/Foundations-of-Diatoni...
[1] https://www.halleonard.com/product/331733/the-perfect-wrong-...
For more detail I highly recommend "The Perfect Wrong Note" by William Westney.
