# natbib, et al by more than one author

I've got some problems with my bibliography style

Code:

\usepackage[square]{natbib}
\usepackage[english,ngerman{babel}
\begin{document}
\chapter{Einleitung}

Text..... \citep{Marley2009}

\bibliography{literatur}
\bibliographystyle{plainnat}
\end{document}

@ARTICLE{Marley2009,
author = {Marley and Smith},
title = {Einsatz von Pulveraktivkohle zur Elimination von Mikroverunreinigungen
aus dem Abwasser},
journal = {blabla},
year = {2009},
owner = {bobmarley},
timestamp = {2012.10.31}
}


I'm getting then

[Marley and Smith2009]

what I want is

[Marley et al 2009], et al

by more than one authors.

Any idea how get that?

-
Welcome to TeX.sx! Which document class do you use? Please complete your given code to a minimal working example (MWE). –  Kurt Nov 7 '12 at 18:15
The plainnat BibTeX style abbreviates authors when there are 3 or more authors. You have to change the BibTeX style. A style that does that is chicago, or you can create you own BibTeX style with custom-bib. For option use a terminal window (command line) and run latex makebst and then follow the prompt.