Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Chapter 3 alone would be worth the cost!

The must have Perl resource. It was written by the the creator of Perl for goodness sake! Offers thorough reference to Perl's rich set of text manipulation features. Not a tutorial but more of a intermediate/expert reference manual. Get Learning Perl(Camel Book) and this book. You will be a perl hacker in no time flat!