books/journals/etc... on dipole surrounds

There was once an ESL (Electrostatic Loudspeaker Ring), but the URL I've got written down is toast. It may still be out there. As I recall, they had instructions on building ESLs.
http://www.geocities.com/ResearchTriangle/8231 has (if you dig deeply enough) info on building ribbon speakers.
http://www.clarkson.edu/~stokessd/quad.html has info on...you guessed it...Quads. I seem to recall that there was something in there about building a pair if you drill down far enough. Power supply supply schematics, perhaps?
http://www.magnepan.com isn't a builder site, but they've got a lot of generalized info on their product that may give you some ideas.
http://www.uspto.gov when all else fails, look at the patents.
Two more general pages:
http://www.hi-fi.com/speaker may have useful links.
http://www.audioxpress.com is the home site for Speaker Builder magazine. I believe they have now folded all their publications into one cover.
I'm not aware of any books on dipoles as surrounds, but I haven't been looking, so there's no telling what's popped up.

Grey