Although we can learn a lot from the internet there's still some great guitar books out there.
Here's my favourites:
This book got me started with fingerpicking instrumentals. It's a great mid level beginners book that has 15 classic songs.
I like this book so much that I've made a video review: How To Captivate An Audience With Fingerstyle Guitar
Acoustic Hit Songs
If you're a singing guitarist and you're looking for some all time classic songs to expand your repertoire then this book is for you. It has the chords and the lyrics, so you need to know a few rhythm patterns to use with each song. I've made a tutorial to help you out with this: 5 Essential Rhythm Guitar Patterns - Video
Music theory has always eluded me. In my first 7 years of learning I didn't care how a C chord was made, I just wanted to play it. This book changed everything. It goes to great lengths to show you how to make the theory relevant to guitar playing. It uses simple terms, practical tests, and the CD is very helpful.
Another finger style book that I enjoy playing through. The book pictured is Volume 1, but there's also a Volume 2. These 2 books are more intermediate than Fingerpicking Pop Hits, but they have some great interpretations, such as Hallelujah, Mad World, Brown Eyed Girl and Nothing Else Matters.
Not related to learning guitar, but here's 3 of my favourite musician autobiographies:
I'm a huge Sting and The Police fan. I enjoyed reading this book because Sting wrote it himself. Here's one of my favourite quotes:
"That night I will go to my room and write a song about a girl. I will call her Roxanne. I will conjure her unpaid from the street below the hotel and cloak her in the romance and the sadness of Rostand’s play, and her creation will change my life.”