Cello Books
The primary book I'm using is Cello Playing for Music Lovers: A Self-Teaching Method.
This is a very thorough book and, so far, I've been enjoying it. Per her recommendation I also picked up 170 Foundation Studies for Violoncello, The Art of Cello Playing: A Complete Textbook Method for Private or Class Instruction and Suzuki Cello School: Cello Part Volume 1
The 170 Foundation Studies are standard practice drills, scales, finger exercises, bowing practice, etc. It's boring stuff but, it's what makes you better. I generally spend 30 minutes a day practicing from this book.
The Art of Cello Playing is a great companion to the Cello Playing. What she doesn't cover, he does. I've been working through both books, trying to keep them at the same level.
The Suzuki book contains simple songs to practice. A nice break from scales. If you take lessons it's likely your teacher will teach from this book (or so I've heard).