Gevorg Grigoryan and Penny Rheingans.
  <b>Point-Based Probabilistic Surfaces to Show Surface
  Uncertainty</b>.
  <i>IEEE Transactions on Visualization and Computer Graphics</i>,
  10(5):564-573, September/October 2004.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/bib/g/Grigoryan-2004-PBP.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Grigoryan-2004-PBP.bib">(bibtex:
  Grigoryan-2004-PBP)</A>.<br />