my $ref_to_array  = \@an_array;
my $ref_to_hash   = \%a_hash;
my $ref_to_scalar = \$a_scalar;

##</code><code>##

my $ref_to_array = [1,2,3,4];
my $ref_to_hash  = { 'key1' => 'val1', 'key2' => 'val2' };
my $ref_to_scalar = \"some string\n";

##</code><code>##

print $ref_to_array->[0];
print $ref_to_hash->{'some_key'};
print ${$ref_to_scalar};