function showNav()
            {
              document.writeln('<CENTER>');
              dispNav('arwl.gif', cPrev, cPrev);
              dispNav('arwu.gif', 'refs', 'References');
              dispNav('arwr.gif', cNext, cNext);
              document.writeln('</CENTER><BR>');
            }

            // -----------------------------------------------------------------

            function dispNav(cGif, cHTML, cAlt) 
            {
              document.write('<A href="' + cHTML + '.html" target="_top">');
              document.writeln('<IMG src="graphics/' + cGif + '" alt="' + cAlt + 
                '" width=50 height=50 border=0 hspace=20></A>');
            }

            // -----------------------------------------------------------------