G. Berkooz, P. J. Holmes, and J. L. Lumley.
  <b>The proper orthogonal decomposition in the analysis of
  turbulent flows</b>.
  <i>Annual Review of Fluid Mechanics</i>, 25:539-575, 1993.
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Berkooz-1993-POD.bib">(bibtex:
  Berkooz-1993-POD)</A>.<br />