\begin{thebibliography}{Ket99}

\bibitem[Ket99]{k-ugpdd-99}
L.~Kettner.
\newblock {Using generic programming for designing a data structure for
  polyhedral surfaces}.
\newblock {\em Comput. Geom. Theory Appl.}, 13:65--90, 1999.

\bibitem[SL02]{sl-qts-02}
Jos Stam and Charles Loop.
\newblock Quad/triangle subdivision, 2002.
\newblock Preprint.

\end{thebibliography}