• http://perlmaven.com/quoted-interpolated-and-escaped-strings-in-perl
• http://perldoc.perl.org/perlop.html
• http://perldoc.perl.org/index-functions-by-cat.html#Functions-for-SCALARs-or-strings
• http://perl101.org/strings.html
• http://www.tutorialspoint.com/perl/perl_scalars.htm