@article{Guthe2004Advanced,
  title = {Advanced Techniques for High-Quality Multi-Resolution Volume Rendering},
  author = {Guthe, Stefan and Stra{\ss}er, Wolfgang},
  journal = {Computer \& Graphics},
  volume = {28},
  number = {1},
  pages = {51--58},
  month = {Feb},
  year = {2004}
}