@Article{eg04-weiskopf-rt,
  author = {Weiskopf, D. and Schafhitzel, T. and Ertl, T.},
  title  = {{GPU-Based Nonlinear Ray Tracing}},
  year   = {2004},
  pages  = {625--633},
  journal = {{Computer Graphics Forum (Eurographics 2004)}},
  volume = {{23}},
  number = {{3}}
}