use XML::XPath;
use XML::XPath::XMLParser;

$xp = XML::XPath->new(filename => 'mlr_648.xml');
$nodeset = $xp->find('//reference/title[@type="journal"]');
foreach my $node ($nodeset->get_nodelist)
{
   $line=XML::XPath::XMLParser::as_string($node);
   if($line =~m!<title type="journal">(.*)</title>!)
   {
       $jb = $1;
   }
   &rep($jb);
}

sub rep
{
   $jabb = $jb;
   open(DAT, "mlr.dat");
   $/=undef;
   $x=<DAT>;
   while($x=~m!(.*)\t(.*)!ig)
   {
       %data = ("$1" => "$2");
       $jname = $data{$jabb};
       if($jname ne "")
       {
           print "<title type=\"journal\">$jname</title>\n";
       }
   }

}