Caroline Ziemkiewicz, Min Chen, David H. Laidlaw, Bernhard Preim, and Daniel
  Weiskopf.
 <b>Open challenges in empirical visualization research</b>.
 In <em>Foundations of Data Visualization</em>. LNCS-Springer, 2020.
  <a href="http://vis.cs.brown.edu/docs/pdf/g/Cziemkiewicz-2020-OCE.pdf.html">(pdf)</a>
  <a href="http://vis.cs.brown.edu/results/bibtex/Cziemkiewicz-2020-OCE.bib">(bibtex:
  Cziemkiewicz-2020-OCE)</a>.