use XML::LibXML;

my $parser = XML::LibXML->new();
my $doc = $parser->parse_file("type_book.xml");

for my $chapter_node ($doc->findnodes('/book/contents'))
{
	print $chapter_node->findvalue('locator[@href ="/book/isbn/979-0-4444-1000-17/book-part/chapter/bk444444ch1?releaseStatus=RELEASED"]/@title');	
}