Nathan Cabot Hale.
  <i><b>Abstraction in Art and Nature</b></i>.
  Dover Publications, Incorporated, 1993.
  <A HREF="http://vis.cs.brown.edu/docs/pdf/bib/g/Hale-1993-AAN.pdf.html">(pdf)</A>
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Hale-1993-AAN.bib">(bibtex:
  Hale-1993-AAN)</A>.<br />