That's correct. There is an HTML version, but it only seems to be available for reading on-line in a "page by page" manner. I downloaded the maps from that, and added them to the text version which is at PG.
There would be nothing particularly to gain from an HTML version of the book's text, because all it has, over the text version, are italics, which are marked in the usual PG manner of _italics_ in the text version. Obviously I've converted these back to proper italics in my version. The main thing the PG version lacks are the maps, which are in the HTML version.