LaTeX.org

Hallo everybody,

I want to use the bibliographystyle natbib. When I use \citep{]}, it just gives me a question mark at the place where it supposses to cite. Here is my latex preamble:

\documentclass[
paper=A4, % Stellt auf A4-Papier ein
pagesize, % Diese Option reicht die Papiergröße an alle ...