How I came across "A Princess of Mars" initially, was that I recently saw a comic book titled
"Warlord of Mars" (by Dynamite Entertainment) which I thought had really cool artwork. So I picked up the first issue which was for $1.
I did some googling online about this comic title, and found out that it was a 12-issue mini series adaptation of "A Princess of Mars". Previously, I didn't pay much attention at all to any of Edgar Rice Burroughs' other work besides Tarzan.
Nevertheless, I'm glad I did come across "A Princess of Mars" in a roundabout way recently. Just from what I've read so far, I can see how huge of an influence this book had on 20th century modern science fiction and fantasy writing (and other media). I can see hints of where Superman, Han Solo, orcs, Elric, Conan,
Kull, D&D,
the Warlord (1970's -> 1980's DC comic series), etc ... were possibly influenced by.