This is a method book that covers both the theory of jazz harmony, and how to practice the application of these concepts in your playing. I listed it as suitable for intermediates because you should know how to read music and have an idea what a scale, chord, and interval are before even getting in the same room with this book.
This is perhaps the most comprehensive resource for those wanting to play jazz. Mark Levine is a pianist, I believe, and he covers all the basic ground that you would expect - intervals, triads, modes, common jazz progressions, chord-scales, and such, but each topic has numerous examples from real players. Not only that, but Mark provides exercises and practice ideas to guide you in how to absorb these concepts into your playing. Even as a simple reference guide, it's incredibly thorough.
By the way, I got permission from Mark and Sher Music Co. to post
an interactive excerpt from this book on WholeNote.com. This particular lesson covers the use of 7th chord sequences. Check it out, and you'll see what I mean about how thorough and applicable the examples are - and this excerpt is just 3-4 pages out of a 500 page book!