@Article{SCI:Cal2008a,
  author =    "S.P. Callahan and J.H. Callahan and C.E.
              Scheidegger and C.T. Silva",
  title =     "Direct Volume Rendering: A 3D Plotting Technique
              for Scientific Data",
  journal =   "Computing in Science and Engineering",
  volume =    "10",
  number =    "1",
  pages =     "88--92",
  year =      "2008",
  url =       "http://www.sci.utah.edu/publications/callahan08/cise08.pdf",
}