It sounds like you probably don't need to include "The World the Children Made" in your bibliography, since that's simply an older title for "The Veldt." (Bradbury's short story was originally published with the title "The World the Children Made" in a September 1950 issue of the Saturday Evening Post, then republished a year later in his anthology The Illustrated Man under the title "The Veldt.") That said, if the version of the story you read had the title "The World the Children Made," you're welcome to cite the work under that title. Whether you cite it as a journal article or as an anthology depends on where you found the short story. If you found it in an ancient copy of the Saturday Evening Post (very cool), you can enter it under "magazine" (probably not "journal article"). If you found it online, opt for website. And if you found it in an anthology, go with "chapter/anthology." It all depends on you!