Anne Treisman.
  <b>Search, Similarity and Integration of Features Between and
  Within Dimensions</b>.
  <i>Journal of Experimental Psychology: Human Perception and
  Performance</i>, 17(3):652-676, 1991.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/bib/g/Treisman-1991-SSI.pdf.html">(pdf)</A> <A HREF="http://vis.cs.brown.edu/results/bibtex/Treisman-1991-SSI.bib">(bibtex:
  Treisman-1991-SSI)</A>.<br />