\newcommand{\etalchar}[1]{$^{#1}$}
\begin{thebibliography}{DEG{\etalchar{+}}}

\bibitem[DEG{\etalchar{+}}]{KoutsofiosNorth:2002}
D.~Dobkin, J.~Ellson, E.~Gansner, E.~Koutsofios, S.~North, and G.~Woodhull.
\newblock Graphviz - graph drawing programs.
\newblock Technical report, AT\&T Research and Lucent Bell Labs.
\newblock http://www.graphviz.org/.

\end{thebibliography}
