What is a good reference book for English idioms?

The language is changing so rapidly and there are so many issues, such a regionalitsms, that I would use the web for research. On a site such a fluther, I come across some expressions that I am not familiar with and simply check with Google.

edit; regionalisms

A Dictionary of Slang and Unconventional English is the classic text though it is UK based.

Like @gailcalled said, it’s better to use the internet. I haven’t found any books that are as comprehensive or up-to-date as I want them to be, but the internet has it all.

Thanks for the suggestions.

While I agree that everything and anything can be found on the internet, I’m interested in a book precisely because of the potential for information overload. I like having printed reference materials on hand because they don’t require me to do the vetting and sorting required of vast quantities of information retrieved by internet searches. Also, I think what a printed source sacrifices in terms of currentness and comprehensiveness is made up for by reliability and trustworthiness—generally speaking a printed source has been edited and reviewed with a little more care and by more pairs of eyes than a lot of the information floating around the web. I’m also a bit of a bibliophile with a nerdy latent love of dictionaries. But maybe I’m just old fashioned?

I just got a hold of this. It isn’t specifically English but it’s a great reference for idioms of the world.

Richard Lederer doesn’t always talk about the origins of idioms, but is an amazing storyteller when it comes to explaining the oddities, in and outs, and everything you’ve never known you wanted to know about words.
Be sure to check out all his books—they’re unusual in that they all are stand-alone books, but really work together to enhance understanding of the craziness of English :)

What about this? And here is an e-book that you supposedly can download?

Thanks for the recommendations!

@ladymia69—Have you used or do you own the Scholastic Dictionary of Idioms? I’ve been mulling over buying it, but I’m worried it might be too kid oriented.