#! perl
use strict;
use warnings;

my %hash = ( X => [ qw( A B   ) ],
             Y => [ qw( C D E ) ],
             Z => [ qw( F G H ) ], );

for my $key (sort keys %hash)
{
    my $array_ref = $hash{$key};
    print "$_ $key, " for @$array_ref;
}