Celtic cross artwork used for Coloring for Tranquility, a 44 page adult coloring book. Note that I have not contributed any of the interior artwork for the book, just the cover art.
However, if you like adult colouring books, don't miss out on my series with Dover! Celtic Nature Designs, Celtic Mandalas (14,000 copies sold!), Celtic Crosses and Trees of Life! If you're looking for downloadable pages to color, check out my Etsy store which has PDF pages you can download for only $0.99 - dragons, crosses, mandalas, animals and more!