use strict;
use warnings;

my %book = (
		'name' => 'abc',
		'author' => 'monk',
		'isbn' => '123-890',
		'issn' => '@issn',           
		);

my %chapter = (
		'title' => 'xyz',
		'page' => '90',                
		);

$chapter{book} = \%book;

print $chapter{book}{name},"\n";