In terms of books, the Trevor Owen one is still the best and most thorough overview. (Someone borrowed mine and didn't return it ... and I think it's out of print now.) There are other books which discuss individual customs, or overviews of specific localities, but can't think of anything comprehensive. And, of course, quite a few of them are in Welsh, so TO's is still the best for the English language market.

Seems to me that there's a 'full' version and a 'condensed' version.

You looking for anything in particular?

sian