what's your favourite book(or E-book) that you've learned so much from about theories?

I'm not looking for a book (or PDF) for beginners, I know how to use modes and how to make a nice chord progression in a specific key, I need a book that explain more about harmonies and more advanced stuff, but easy to understand, not really complicated.

I prefer PDFs

thnx in advanced

The Jazz Theory book by Mark Levine is the only theory book i have, and the only one i'll ever need. Check that one out, it will last you a lifetime.
Fusion and jazz musician, a fan of most music.

Quote by Guthrie Govan
“If you steal from one person it's theft, and if you steal from lots of people it's research”

Quote by Chick Corea
"Only play what you hear. If you don't hear anything, don't play anything."
The Mark Levine book is good. Another good one is Music Theory For Dummies. Also check out Everything You Wanted to Know About Music Theory, But Were Afraid to Ask. Seems I have another good one, but I can't see it in my book shelf from here.
Yeah, I like The Jazz Theory Book. Fundamentals of Musical Composition by Schoenberg and Gradus Ad Parnassum by Fux are also really really good musical literature.
I'm a big big fan of "Songwriting Secrets of the Beatles" by Pedler. Lots of great explanations and examples of harmonic concepts. Probably all you need to know, theorywise, if you play rock, blues, folk, or pop. (Expensive, but SUPER worth it).