Books, articles on Maxima?



Are there any published books or articles on Maxima and its use - is there
any database of such publications?  It seems to me that Maxima, being the
only really general-purpose GPL CAS with a reasonable user-base, would be
well served by a nice book (maybe published by O'Reilly).  Or maybe
everybody out there is busily writing one?

-Alasdair