Intermediate Perl
Learning Perl Objects, References & Modules, published in 2003 by O'Reilly (ISBN 0596004788), is a follow-up to the highly popular Learning Perl book by Randal L. Schwartz and Tom Phoenix. Just as Learning Perl features a Llama on its cover, its follow-up features an Alpaca.
This book is written in very much the same style as its predecessor. It picks up right where Learning Perl left off, and takes the reader from the most basic features of Perl references all the way through to creating perl modules and distributing them to CPAN.
In March 2006 a second edition of this book was published under the new title Intermediate Perl (ISBN 0596102062).