Assignment             Create a Reference              Dereference             Dereference with Arrow
$sca= 5;               $p = \$sca;                     print $$p;    
@arr=(4,5,6);          $p = \@arr;                     print @$p;              $p->[0]
                                                       print $$p[0];          
%hash=(key=>'value');  $p = \%hash;                    print %$p;              $p->{key}
                                                       print $$p{key};