@InProceedings{vis97-wester2,
  author = 	 {Westermann, R. and Ertl, T.},
  title = 	 {{Visibility Ordering of Volume Primitves by Polygon Drawing}},
  editor =       "Yagel, R. and Hagen, H.",
  booktitle =    "Visualization '97",
  year = 	 1997,
  publisher =    "IEEE Computer Society Press"
}