I read four different books for this exam they all helped on different parts. I didn't feel any of the books covered everything I ran into on the exam. Probably the one that helped the most was
File System Forensic Analysis by Brian Carrier. The other three were:
Forensics Discovery (Dan Farmer)
Read Digital Forensics (Keith J. Jones, Richard Bejtlich, & Curtis W. Rose)
Incident Response and Computer Forensics, Second Edition (Chris Prosise, Kevin Mandia, & Matt Pepe)