Disney’s visually spectacular interplanetary epic John Carter opened in theaters this weekend with Taylor Kitsch playing the titular hero who finds himself lost in a strange land, Lynn Collins portraying a Martian princess and Willem Dafoe as a towering alien warlord. Regardless of how well John Carter performs at the box office, none of it would have been possible without author Edgar Rice Burroughs’ long-running series featuring the exploits of an Earthling on Barsoom. It’s taken almost 100 years to translate Burroughs’ vision to the big screen, but I predict that the novel will enjoy a much longer lifespan than the film. We’ve brought you trailers, images, clips, posters and interviews, but none of it would exist without the original book, “A Princess of Mars,” which the Library of Congress has made available to read for free online. Definitely go check out the film while it’s still in theaters, but do yourself a favor and read up on this classic series as well. Hit the jump to see a PSA from the ad council reminding us that books still exist.