Bei einigen Hundert Einträgen möchte ich das aber gerne vermeiden. Gibt es da eine Möglichkeit?
Und wenn ich schon dabei bin. Ist es möglich, die letzte beidem Autoren durch ein & anstatt ein Komma zu trennen ?
Ich habe mich hier mal freimütig an einer foo.bib aus dem Forum bedient.
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% Welcome to Overleaf --- just edit your LaTeX on the left,
% and we'll compile it for you on the right. If you give
% someone the link to this page, they can edit at the same
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\RequirePackage{filecontents}
\begin{filecontents}{foo.bib} 
@ARTICLE{Ausubel2004, 
  author = {Cramton, Peter and Ausubel, Lawrence M. and Milgrom, Paul}, 
  title = {The Clock-Proxy Auction: A Practical Combinatorial Auction Design}, 
  year = {2006}, 
  volume = {Combinatorial auctions}, 
  pages = {115-138}, 
  chapter = {5}, 
  editor = {Peter Cramton and Yoav Shoham and Richard Steinberg}, 
  institution = {University of Maryland, Department of Economics -- Peter Cramton}, 
  keywords = {Auctions; Combinatorial Auctions; Market Design; Clock Auctions}, 
  publisher = {MIT Press}, 
  timestamp = {2013.07.10}, 
  url = {http://ideas.repec.org/p/pcc/pccumd/04mit5.html} 
} 
@ARTICLE{Cramton2011, 
author = {Cramton, Peter and Kwerel, Evan and Rosston, Gregory and Skrzypacz, 
Andrzej}, 
title = {Using spectrum auctions to enhance competition in wireless services}, 
journal = {Journal of Law and Economics}, 
year = {2011}, 
volume = {54}, 
timestamp = {2013.07.17} 
} 
\end{filecontents} 
\documentclass[listof=numbered,numbers=noenddot,
bibliography=numbered,chapterprefix=false,11pt]{scrreprt} 
\usepackage[utf8]{inputenc} 
\usepackage[T1]{fontenc} 
\usepackage[english,ngerman]{babel} 
\usepackage[maxbibnames=9, maxcitenames=1 ,bibstyle=authoryear,citestyle=authoryear-icomp,uniquename=false,uniquelist=false,sorting=nyt,
sortcase=false,isbn=false,url=false,doi=false,backend=biber]{biblatex}
\usepackage{csquotes} 
\DefineBibliographyStrings{ngerman}{andothers={et\addabbrvspace al\adddot}}      % et al. statt u.a. 
\setlength{\bibitemsep}{1em}     % Abstand zwischen den Literaturangaben 
\setlength{\bibhang}{2em}        % Einzug nach jeweils erster Zeile 
\renewcommand*{\labelnamepunct}{\addcolon\space}
\renewcommand*{\mkbibnamefamily}[1]{\textsc{#1}}
\DefineBibliographyStrings{ngerman}{andothers={et\addabbrvspace al\adddot}}  
\renewcommand*{\multinamedelim}{\space\addcomma\space}						%dür das & statt und in Biblifragfie
\renewcommand*{\finalnamedelim}{\space\addcomma\space}
\addbibresource{foo.bib} 
\begin{document} 
Bla bla \parencite{Ausubel2004}. Foo bar \parencite{Cramton2011}
\clearpage 
\printbibliography 
\end{document}
