perlintro#Simple matching->Extracting matches, perlrequick, perlretut, Modern Perl pdf page 97, http://learn.perl.org/books/beginning-perl/ chapter 5, Learn Perl in about 2 hours 30 minutes , PLEAC - Programming Language Examples Alike Cookbook..., Interactive Perl tutorials http://perltuts.com/tutorials/quick-start/regular-expressions, Learn How to Program Perl Lesson 6: Regex