If you can, buy through your local independent bookseller. They could really use your support. Find your local store at booksense.com.
You can look for my books at any bookstore. If it's not on the shelves, they can order it for you - just ask! You can also purchase through these online booksellers:Amazon Barnes & Noble Simon and Schuster The audio book versions of the Books of Umber trilogy are amazing. (Really: They were all honored as Amazing Audio Books by the American Library Association.) Get them here - where you can also listen to samples: Audible.com (Books of Umber audio books)