Connor Gramazio, Karen B. Schloss, and David H. Laidlaw.
 <b>The relation between visualization size, grouping, and user
  performance</b>.
 In <em>IEEE Transactions on Visualization and Computer Graphics</em>,
  volume&nbsp;20, pages 1953--1962, 2014.
  <a href="http://vis.cs.brown.edu/docs/pdf/g/Gramazio-2014-RVS.pdf.html">(pdf)</a>
  <a href="http://vis.cs.brown.edu/results/bibtex/Gramazio-2014-RVS.bib">(bibtex:
  Gramazio-2014-RVS)</a>.