@Article{SCI:Cal2005a,
  author =    "S.P. Callahan and M. Ikits and J.L.D. Comba and
              C.T. Silva",
  title =     "Hardware-Assisted Visibility Ordering for
              Unstructured Volume Rendering",
  journal =   j-TVCG,
  volume =    "11",
  number =    "3",
  pages =     "285--295",
  year =      "2005",
  publisher = "{IEEE} Educational Activities Department",
  issn =      "1077-2626",
  keywords =  "scalar field methods, volume rendering, visibility
              ordering, GPU, tetrahedral meshes, unstructured
              volume rendering",
  url =       "http://www.sci.utah.edu/publications/stevec05/HAVS.pdf",
}