Chaomei Chen.
  <b>Top 10 Unsolved Information Visualization Problems</b>.
  <i>IEEE Computer Graphics and Applications</i>, 25(4):12-16,
  July/August 2005.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/bib/g/Chen-2005-TUI.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Chen-2005-TUI.bib">(bibtex:
  Chen-2005-TUI)</A>.<br />