Kepler and the Music of the Spheres

Does anyone know of good books about Johannes Kepler? His work on the planetary laws linked the harmonic series with the proportional speeds of the planets - this is an old observation that still, to my satisfaction, has yet to meet a satisfying scientific conclusion. The books I've researched on Kepler center around his life, with just one or two explaining his contributions. He's mentioned heaps in other books for brief moments, but never long enough for deep discussion. Any knowledge out there? BB