Stephen Mann and Alyn Rockwood.
  <b>Computing Singularities of 3D Vector Fields with Geometric
  Algebra</b>.
  In <i>VIS</i>. IEEE, 2002.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/g/Mann-2002-CSO.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Mann-2002-CSO.bib">(bibtex:
  Mann-2002-CSO)</A>.<br />