Reddit mentions of Joe Pass Guitar Style: Learn the Sound of Modern Harmony & Melody

Not Internet, but you could and probably should spring for the Joe Pass Guitar Style book. The first part of the book is all harmony related and has all of these extension/substitution principles plus a whole lot more.

I've used these:

http://www.amazon.com/gp/product/1619280159/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1

http://www.amazon.com/gp/product/0739018655/ref=oh_details_o06_s00_i00?ie=UTF8&psc=1

http://www.amazon.com/gp/product/1883217040/ref=oh_details_o07_s00_i00?ie=UTF8&psc=1

Mark Levine's Jazz Theory Book is good - probably one of the better books of its type out there.

I would highly recommend The Joe Pass Guitar Style by Joe Pass and Bill Thrasher. The theory is "old school" - no discussion of modes, for example - but if you have basic knowledge of major keys and simple chord construction you'll be able to piece your way through. I picked it up after two years of playing guitar and two semesters of high school music theory and didn't find it difficult to follow. There is a lot of info and it's condensed, but also hands-on useful materiel such as written out solos on regular blues, minor blues, "Parker" blues (Blues for Alice), and 3/4 blues a-la the tune "Bluesette."

After years of fascination with the esoteric I lost my taste for Mick Goodrick's Advancing Guitarist and sold it. I'm not saying it has no use, but overall I would not put it at the top of my list of recommendations. The same goes for Dennis Sandole's book Guitar Lore, another extremely over-hyped book IMO.

Another book I used a lot in my formative years is Improvising Jazz by Jerry Coker. That was where I learned about chord scale relationships and the Roman numeral system for analyzing chord changes, which is super useful for learning tunes in all keys.