@Article{cpc09-mueller,
  author = {Müller, T. and Grave, F.},
  title  = {{Motion4D - A library for lightrays and timelike worldlines in the theory of relativity}},
  year   = {2009},
  pages  = {2355-2360},
  journal = {{Computer Physics Communications}},
  volume = {{180}},
  doi = {{10.1016/j.cpc.2009.07.014}}
}