Gai Perry's book is called Color from the Heart:Seven Great Ways to Make Quilts with Colors You Love.
Also, there is a book called Quilting and Color Made Easy, and a book called Color Harmony: A Guide to Creative Color Combinations.
I looked these up on Amazon. I am self-taught on color mixing. Really it comes down to trial and error, but reading one or two books on the theory help a lot.
Jinny Beyer has one also, I don't remember the name, but she had a section where she explained how multiple colors are printed on fabric. The photos showed how very different a print looked with just one color missing. What a difference it made when they showed the finished product. It's worth looking at. Maybe you could find them at your local library?