Hal Leonard Music Theory & History
If you're looking for a recommendation, just take a look at the long list of best sellers. For biographies, check out the incredibly written Hal Leonard Guitar World Presents: Stevie Ray Vaughan Book or the SkyDog: The Duane Allman Story (Book) to delve deep into minds of a pair of musical geniuses. If you're looking for theory, consider the Hal Leonard Pocket Music Theory Book and the Hal Leonard The Chord Wheel for a compressive look at the fundamentals. There are even games that can make learning fun like the All-Purpose Music Flashcards, Rhythm Bingo Level 1, and Music Symbol Bingo.
Hal Leonard is a name you can trust when it comes to music theory and history. Responsible for the development of millions of musicians over the past half century, their material was created to be accessible and approachable so everyone has an opportunity to learn. Becoming a great musician isn't always easy, but with a strong understanding of the basics you'll be well on your way.