I just discovered that Marvel released a John Carter of Mars Omnibus featuring all the comics they published in the 1970s.
Here is cover and as you could expect, Davis does a superb job capturing Carter, Tars Tarkas, and Barsoom. Notice that Dejah Thoris here doesn't match the version in the Marvel Comics tales.
Here is the pencil version of this artwork. I am not quite sure but I believe that Davis drew this a while back even before the current JC mania in advance of the movie. Alan writes on his website that "ERB's Mars books have been a favourite for many years and I have often thought about how I might handle the stories. This was one attempt to come up with a slightly different look from the usual comic book versions of the characters."
For more Marvel Comics with John Carter, check out my article on Giant-Size Marvel titled Gil Kane and Dave Cockrum on John Carter Warlord of Mars. Nuff Said!