These three books are available for quick reference when I am designing or creating an art piece.
I keep a small library of art and design books, in addition to back issues of Communication Arts and the now deceased, but invaluable, Art Lies quarterly.
Frankly, there's only so much you can take away from the internet. Looking at something on a screen is a different experience from a lush print in the pages of your favorite book. Books are tactile and physical, like art, and they bolster creativity in different way.
1. The Interaction of Color, Josef Albers
Short, but densely packed de-facto source of color theory. I can read this book again and again and discover something new and thought-provoking about the psychology of color. My unabridged version also contains a few prints of selected color plates.
2. African Art from The Menil Collection, The Menil Collection
The Menil Collection houses one of the largest assemblages of African art pieces in the world. Not only are these sculptures and ornaments stunning in their simplicity and form, but it is awe-inspiring to view art from antiquity and the origins of civilization as we know it. These patterns and symbols reverberate through artwork to this day.
3. Henri Matisse Paper Cut-Outs, The St. Louis Art Museum + The Detroit Institute of Arts
In the final decade of his life, Henri Matisse produced a large volume of paper cut-outs by "drawing with scissors". These are lesser known works than his paintings, but are unrestrained and rhythmic. They are a joy to look at, and, like his drawings, remind me of his unabashed confidence as an artist. (Something we can all take a queue from.)