This book, I refer it as my musical bible, is a well kept secret. Dennis Sandole, who was from Philadelphia, was the "guru" of theory/harmony/teacher during the 50's through the 70's. Anyone who was anyone in the music world, that lived in the Philly area has had some connection with Mr. Sandole including the likes of Coltrane, Bruno, Martino, Federico and the Heath Bros. This book has it all. Theory, Technique, harmony. I was introduced to this book by my latest teacher Mr. Joseph Federico of New Jersey and a whole new world opened for me. I strongly recommend this book for all levels and I shall be inputing some lessons based off of this book.