Edgar Rice Burroughs wrote "pulp fiction" which was printed in black text with a few black "woodcut" line drawings on really cheap pulp paper which started to yellow immediately (like old newspapers). The pulps were a nickle apiece and inspired many late 19th and early 20th Century authors, Samuel Clemens among them. This was the equivalent of comic books from the post Civil War era right up until the 1940s when they figured out how to print in four colored ink and staple on a glossy cover of magazine-quality paper for 5 cents an issue. The comics evolved into "graphic novels" thanks mainly to Marvel Comics and artist Stan Lee. Video Games replaced graphic novels, and the CGI fest movies of today are graphic novels for the digital generation.
In the 1960's, Ace reprinted ERB's Mars novels - plus Tarzan, Pellucidar, Carson of Venus, and all his other characters - in paperbacks that cost $.35 or $.50 each - I had quite a collection. But if you didn't read the originals as a teenager, don't bother, they won't hold an adult's interest.