The Physics of Barbershop Sound. - A manuscript supposedly describing how overtones are produced during close harmony singing, to the extend of explaining which overtones are being produced on what intervals and why. Would love to know more about that. $10
The Artist's Way - This book has been repeatedly recommended to me by people I respect. It's known for its practical and effective exercises (which I love), as well as for having the tendency to dwell in the so-called divine (which I don't love so much). I'd like to give it a try when my physical health is under control.
Deke Sharon and Dylan Bell - A Cappella Arranging. With these names on the cover, this is a no-brainer. In their own words, it's meant to be the definitive work on a cappella arranging. Release date 16 Oct 2012. Hoping it will be made available in Europe as well. $29.99