The fruit of more than 10 years of research and travel throughout Europe and the British Isles, here is the first single volume to provide a full survey of Celtic arts and crafts from 700 B.C. to A.D. 700. 452 illustrations, 24 in color.
Using this one as research; but wow, so far it's fascinating.
This one was a great reference. I might have to purchase it for review at a more leisurely pace. Maybe it was just because the topic was already interesting to me, but this text book/history wasn't as cut and try as those types of books seem to be.