@Article{SCI:Cal2006e,
  author =    "S.P. Callahan and L. Bavoil and V. Pascucci and
              C.T. Silva",
  title =     "Progressive Volume Rendering of Large Unstructured
              Grids",
  journal =   "{IEEE} Transactions on Visualization and Computer
              Graphics",
  volume =    "12",
  number =    "5",
  pages =     "1307--1314",
  year =      "2006",
  note =      "Updated version of UUSCI-2006-019.",
  keywords =  "volume rendering",
  url =       "http://www.sci.utah.edu/publications/stevec06/pro-havs.pdf",
}