Eismann, Katrin. Photoshop Masking and Compositing
     New Riders, 2005

Fraser, Bruce. Real World Camera Raw with Adobe Photoshop CS2
     Peachpit Press, 2005

Giordan, Daniel. The Art of Photoshop
     Sams Publishing, 2006.

Kelby, Scott. The Photoshop CS2 Book
     New Riders / Peachpit, 2005.