@elputisimoamo This is based on a book by Edgar Rice Burroughs (1875-1950), an American pulp adventure writer. His most famous character is probably Tarzan.
Unfortunately it seems this won't ever be completed. What we have now is all we'll ever get.
The artist, James Killian Spratt, died some years ago (I remember reading his online obituary somewhere).
The original gallery of this stuff was available at the online ERBzine site (http://www.erbzine.com/mag13/1301.html). I'm not sure if geardog found these particular images elsewhere. Mr. Spratt also did some sculpting of his visions of John Carter's Barsoom for a board game too, if you follow the links.
Pasting here some relevant info about the author from Dan Nadel's (curator, Lucas Museum of Narrative Art) website: "From 2000 to his death in 2016, James Killian Spratt dedicated himself to drawing a graphic adaption of Edgar Rice Burroughs’s pulp classic A Princess of Mars. As yet unpublished, and as lewd and camp as the original, Spratt’s version is among the greatest pieces of fan art ever created. Fans of the fan, painter Carroll Dunham and I borrowed the artist’s original notebooks from his son to curate—and comment upon—this first printed portal into Spratt’s high-strung and well-hung metaverse. Download the essays and images at this link" (link - http://dnadel.com/wp-content/uploads/2022/05/BLAU-INTERNATIONAL_No6-EXCERPT.pdf )