@ARTICLE{HP04,
  author = {Klaus Hildebrandt and Konrad Polthier},
  title = {Anisotropic Filtering of Non-Linear Surface Features},
  journal = {Computer Graphics Forum},
  year = {2004},
  volume = {23},
  pages = {391--400},
  number = {3},
  note = {Proceedings of Eurographics}
}