The complete Perl documentation is available with the Perl distribution. If you have Perl installed locally, you probably have the documentation installed as well: type man perl if you're on a system resembling Unix. This will lead you to other important man pages, including how to set your $MANPATH. If you're not on a Unix system, access to the documentation will be different; for example, documentation might only be in HTML format. All proper Perl installations have fully-accessible documentation.
You might also try perldoc perl in case your system doesn't have a proper man command, or it's been misinstalled. If that doesn't work, try looking in /usr/local/lib/perl5/pod for documentation.
If all else fails, consult http://perldoc.cpan.org/ or http://www.perldoc.com/ both offer the complete documentation in html format.
Many good books have been written about Perl--see the section below for more details.
Tutorial documents are included in current or upcoming Perl releases include perltoot for objects or perlboot for a beginner's approach to objects, perlopentut for file opening semantics, perlreftut for managing references, perlretut for regular expressions, perlthrtut for threads, perldebtut for debugging, and perlxstut for linking C and Perl together. There may be more by the time you read this. The following URLs might also be of assistance:
http://perldoc.cpan.org/
http://www.perldoc.com/
http://reference.perl.com/query.cgi?tutorials
http://bookmarks.cpan.org/search.cgi?cat=Training%2FTutorials