1\begin{thebibliography}{}
2
3\bibitem[OPS98]{OPS98}
4   J. Opgenorth, W. Plesken, and T. Schulz.
5   \newblock Crystallographic Algorithms and Tables.
6   \newblock {\em Acta Cryst A} 54, 517--531 (1998).
7
8\end{thebibliography}
9