#!/usr/bin/perl
use warnings;
use strict;
my $a = do {local $/; <DATA>};

use XML::XPath;
use XML::XPath::XMLParser;
    
    my $xp = XML::XPath->new(xml => $a);
    
    my $nodeset = $xp->find('//@author'); # find all authors
    

    foreach my $node ($nodeset->get_nodelist) {
        print $node->getNodeValue."\n\n"; }