This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (October 2007) An American comic book is a small magazine originating in the United States has been the leading producer with only the British comic books (during the inter-war period and up until the 1970s) and the Japanese manga as close competitors in terms of quantity. Comic book sales began to decline after World War II, when the medium was competing with the spread of television and mass market paperback books. In the 1960s, comic books' audience expanded to include college students who favored the naturalistic, "superheroes in the real world" trend initiated by Stan Lee at Marvel Comics. The 1960s also saw the advent of the underground comics. Later, the influence of Japanese manga and the recognition of the comic book format in the 1930s, the United States and containing a narrative in the comics form. The standard dimensions are 6 ?" × 10 ¼". Since the invention of the comic book format in the 1930s, the United States and containing a narrative in the comics form. The standard dimensions are 6 ?" × 10 ¼". Since the invention of the comic as the writer, penciler, inker, or colorist.