LaTeX Forum

\documentclass[12pt, titlepage]{article}
\usepackage{german}
\usepackage{amsmath}
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\usepackage{dsfont}
\usepackage{mnsymbol}
\usepackage{enumitem}
\usepackage{graphicx}
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\usepackage{a4wide}
\usepackage{wasysym}
\usepackage{xcolor}
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\usepackage{url}
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\usepackage{floatflt}
\usepackage{caption}
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\usepackage{wrapfig}
\usepackage{natbib}


\begin{document}

Texttexttext \cite{buch1} Texttexttext

\bibliographystyle{alpha}
\bibliography{Literatur}

\end{document}

This is BibTeX, Version 0.99d (Web2C 2011)
The top-level auxiliary file: Portfolio.aux
The style file: alpha.bst
Database file #1: Literatur.bib
A bad cross reference---entry "Dem2008"
refers to entry "Dem_Exp_1", which doesn't exist
Warning--I didn't find a database entry for "Dem_Exp_1"
(There was 1 error message)

\listfiles
\documentclass[12pt,titlepage]{article}% besser scrartcl für Europa
%\usepackage{}% veraltet besser babel
\usepackage[german]{babel}

\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{dsfont}
\usepackage{MnSymbol}% auf Schreibweise achten!
\usepackage{enumitem}
\usepackage{graphicx}
\usepackage{soul}
\usepackage{multicol}
\usepackage{a4wide}% veraltet, sollte nicht mehr verwendet werden
\usepackage{wasysym}
\usepackage{xcolor}
\usepackage{fancyvrb}
\usepackage{url}
\usepackage{fancybox}
\usepackage{floatflt}
\usepackage{caption}
\usepackage{subfig}
\usepackage{wrapfig}
\usepackage{float}
\usepackage{wrapfig}
\usepackage{natbib}

\usepackage{filecontents}
\begin{filecontents}{Literatur.bib}
@book{buch1,
 author = {Mittelbach, Frank and Goossens, Michel and Braams, Johannes},
 year = {2010},
 title = {Der Latex-Begleiter},
 publisher = {Pearson Studium},
 price = {EUR 39.95, EUR 41.10 (AT), sfr 67.00 (freier Pr.)},
 address = {M{\"u}nchen},
 edition = {2., {\"u}berarb. und erw. Auf\/l., [Nachdr.], Baf{\"o}g-Ausg.},
 isbn = {978-3-8273-7166-9},
 series = {ST - scientific tools}
}
\end{filecontents}

\begin{document}

Texttexttext \cite{buch1} Texttexttext

\bibliographystyle{alpha}
\bibliography{Literatur}

\end{document}

\bibliography{Pfad zu deiner Jabref/Literatur} 

\begin{filecontents}{Literatur-Test.bib}