New York The Museum of Modern Art, 1973. Issued in conjunction with the exhibition at The Museum of Modern Art, New York, September - November 1973; notable for the appendix ("Kelly and Camouflage"). Includes bibliography and index.
If you're familiar with Kelly's work, but don't know the background story behind much of it, you may enjoy reading this. As an artist (or wanna-be), I am finding the stories in the expanded captions of the plates as to how he came up with the designs to be really interesting. I love some of his work just for what it is, but knowing why he painted some of the pieces he did makes them so much more alive and interesting.
Clearly not the best catalog, as it's full of black and white photographs of work that is often about color, but worth reading for Kelly's artistic biography (however, don't expect much about his personal life - there's not a single mention of the fact that he was gay, for example).
I read this from a PDF that MoMA made available, Google it and save yourself the money!