P. T. Callaghan.
  <i><b>Principles of nuclear magnetic resonance microscopy</b></i>.
  Oxford, Great Britain, 1993.
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Callaghan-1993-PNM.bib">(bibtex:
  Callaghan-1993-PNM)</A>.<br />