[boost] [phoenix] Where is the documentation?

Is there any definitive documentation for Phoenix? I've found http://www.boost.org/doc/libs/1_35_0/libs/spirit/phoenix/index.html http://spirit.sourceforge.net/dl_docs/phoenix-2/libs/spirit/phoenix/doc/html... and various other web references, but I'm unsure if either is authoritative. Also, are any books about it? Alone the lines of Karlsson's book for Lambda? Thanks, Rob.