* http://www.tutorialspoint.com/perl/perl_arrays.htm
  * http://www.perlboard.de/perlguide/Kap04.html
  * http://perl101.org/arrays.html
  * http://perldoc.perl.org/index-functions-by-cat.html#Functions-for-real-@ARRAYs
  * http://perldoc.perl.org/index-functions-by-cat.html#Functions-for-list-data