@InProceedings{SCI:Wym2003a,
  author =    "C. Wyman and C.D. Hansen",
  title =     "Penumbra Maps: Approximate Soft Shadows in
              Real-Time",
  booktitle = "Eurographics Rendering Symposium",
  pages =     "202--207",
  year =      "2003",
  location =  "Belguim",
  url =       "http://www.sci.utah.edu/publications/wyman03/PenumbraMaps.pdf",
}