Dirty Secrets of the Perl Regex Engine
   Slides from a talk the author presented at TPC and YAPC. Covers the /o flag and re 'eval'.
   http://perl.plover.com/yak/dirty/

How Regexes Work
   An article about how to use regular expressions in Perl by M-J Dominus.
   http://perl.plover.com/Regex/

MakeRegex
   The Perl-module by Hakan Kjellerstrand composes a regex-expression from a list of words.
   http://www.hakank.org/makeregex/

PERL5 Regular Expression Description
   Detailed description written by Tom Christiansen in response to a question posted to comp.lang.perl.misc.
   http://people.bath.ac.uk/ccsnad/perl/everything_to_know/regexps.html

Perl FAQ : Regular Expressions
   Pattern matching and regular expressions.
   http://perldoc.perl.org/perlfaq6.html

Perl Regex
   An introduction covering basic concepts.
   http://www.anaesthetist.com/mnm/perl/regex.htm

Perl Regular Expression Matching is NP-Complete
   A discussion of the complexity of regular expression matching algorithms in Perl.
   http://perl.plover.com/NPC/

Perl Regular Expression Quick Reference
   One-page document containing tabulated summaries of common codes, modifiers, and special characters. [PDF]
   http://www.erudil.com/preqr.pdf

Perl Regular Expression Tutorial
   A tutorial that shows how to use Regular Expressions in Perl.
   http://virtual.park.uga.edu/humcomp/perl/regex2a.html

Perldoc.com - perlre
   Describes the syntax of regular expressions in Perl.
   http://perldoc.perl.org/perlre.html

Perldoc.com - perlretut
   A tutorial for regular expressions in Perl.
   http://perldoc.perl.org/perlretut.html

Regular Expressions
   A description of the patterns used in Perl for pattern matching.
   http://www.cs.cmu.edu/People/rgs/pl-regex.html

perl.perl6.language.regex
   Archive of discussion relating to regular expressions in Perl 6.
   http://www.nntp.perl.org/group/perl.perl6.language.regex/

perlretut
   Basic tutorial, distributed as part of the core documentation.
   http://www.cs.rit.edu/~afb/20013/plc/perl5/doc/perlretut.html