• To use a reference, say $ref, you put {$ref} in place of a variable name (not counting the $, %, or @):

      $scalar      ${$sRef}
      @array       @{$aRef}
      $array[0]    ${$aRef}[0]
      $#array      $#{$aRef}
      %hash        %{$hRef}
      $hash{KEY}   ${$hRef}{KEY}
      @hash{@list} @{$hRef}{@list}
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• If the reference is held in a simple scalar variable, then the { and } can be dropped:

      $scalar      $$sRef
      @array       @$aRef
      $array[0]    $$aRef[0]
      $#array      $#$aRef
      %hash        %$hRef
      $hash{KEY}   $$hRef{KEY}
      @hash{@list} @$hRef{@list}
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• If you are getting a scalar from a hash or array, then you can replace ${$ref} with $ref->:

      $array[0]    $aRef->[0]
      $hash{KEY}   $hRef->{KEY}
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• If the reference is in a hash or array, then you can drop the -> between the adjacent [0] and {KEY}:

      ${$aRef->[0]}[1]    $aRef->[0]->[1]   $aRef->[0][1]
      ${$aRef->[0]}{KEY}  $aRef->[0]->{KEY} $aRef->[0]{KEY}
      ${$hRef->{KEY}}[1]  $hRef->{KEY}->[1] $hRef->{KEY}[1]
      ${$hRef->{A}}{B}    $hRef->{A}->{B}   $hRef->{A}{B}
  [download]

I hope that makes things much clearer.