Holger Theisel, Tino Weinkauf, Hans-Christian Hege, and Hans-Peter Seidel.
  <b>Stream Line and Path Line Oriented Topology for 2D
  Time-Dependent Vector Fields</b>.
  <i>IEEE Visualization</i>, 2004.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/bib/g/Theisel-2004-SLP.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Theisel-2004-SLP.bib">(bibtex:
  Theisel-2004-SLP)</A>.<br />