LaTeX.org

Exactly, that is my point! I dont get "Working Paper" in my references as well.
In fact I use the book environment.
Here is an example, which hopefully helps:

\documentclass[12pt, a4paper, titlepage, reqno, oneside, openany, openbib]{book}%
\usepackage{natbib}
\begin{document}
\chapter ...

Thanks kaiserkarl123,

but editing a bst seems not that easy for a newbie as me.
I have tried to add the following function

FUNCTION {add.wp}
{ "Working paper." }

and added teh function here:
FUNCTION {unpublished}
{ output.bibitem
format.authors "author" output.check
author format.key output ...

Hi there,

I have just searched the forum and the internet for a while but could not find a solution to my bibtex problem. Currently I write a book and use the following bib style:

\bibliographystyle{elsarticle-harv}

Everything works fine, except for unpublished work / working paper. Here an ...