That info comes from Daithi O hOgain's The Celts A History. Google Books has it here:
http://books.google.com/books?id=-yd...elts+a+history
A great book, and easy to follow. Not an entry level book, but not a high end scholarly book. Honestly, the best sources cannot typically be found online, for free at least. If you have a good university library you can really read about some wonderful ideas, interpretations, topics, and ideas about the Celts.
Bookmarks