Der Dativ ist dem Genitv sein Tod (German: "the dative case is the genitive case's death") is a book series written by Bastian Sick which deals with doubtful cases of grammar, orthography, and punctuation. Because of that, the writer wants to fight against unthinking habit and what he believes to be a change to a lower state of the language. The book came from a collection of Zwiebelfisch-collumns of Bastian Sick, which appear weekly in the Spiegel Online. At present, the second and third volumes are available. The volumes are from one time to another at the top of book sales lists.