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. has (if you dig deeply enough) info on building ribbon speakers. has info 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? isn't a builder site, but they've got a lot of generalized info on their product that may give you some ideas. when all else fails, look at the patents.
Two more general pages: may have useful links. 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.