Stanford, Calif. - A federal court in New York on Monday heard arguments from Harry Potter author J.K. Rowling, who along with Warner Bros. (NYSE: TWX) has filed suit to prevent the publication of a reference guide to the series, claiming its creator has stolen her work. The defendant, RDR Books, argued that its print version of "The Harry Potter Lexicon," based on school librarian and Harry Potter fan Steven Vander Ark's Web resource of the same name, is a legal "fair use" or Rowling's works.