@Article{SCI:Zho2012a,
  author =    "L. Zhou and M. Schott and C.D. Hansen",
  title =     "Transfer Function Combinations",
  journal =   "Computers and Graphics",
  volume =    "36",
  number =    "6",
  pages =     "596--606",
  year =      "2012",
  month =     "October",
  doi =       "10.1016/j.cag.2012.02.007",
  keywords =  "transfer function, volume rendering,
              classification, user interface, nih, scidac,
              kaust",
  url =       "http://www.sci.utah.edu/publications/zhou12/Zhou_elsarticle-TFcombinations_CandG2012.pdf",
}