Alistair Sutcliffe, Brian Gault, and Jae-Eun Shin.
 <b>Presence, memory and interaction in virtual environments</b>.
 <em>International Journal of Human-Computer Studies</em>,
  62(3):307--327, March 2005.
  <a href="http://vis.cs.brown.edu/docs/pdf/bib/g/Sutcliffe-2005-PMI.pdf.html">(pdf)</a>
  <a href="http://vis.cs.brown.edu/results/bibtex/Sutcliffe-2005-PMI.bib">(bibtex:
  Sutcliffe-2005-PMI)</a>.