If you'd like to learn more about Perl, here are some related publications that we (somewhat sheepishly) recommend:
A tutorial introduction to Perl for programmers interested in learning Perl from scratch. It's a good starting point if this book is over your head. Erik Olson refurbished this book for Windows systems, called Learning Perl on Win32 Systems.
This book is indispensable for every Perl programmer. Coauthored by Perl's creator, this classic reference is the authoritative guide to Perl's syntax, functions, modules, references, invocation options, and much more.
A tutorial for advanced regular expressions, network programming, GUI programming with Tk, and Perl internals. If the Cookbook isn't challenging you, buy a copy of the Panther.
This book is dedicated to explaining regular expressions from a practical perspective. It not only covers general regular expressions and Perl patterns very well, it also compares and contrasts these with those used in other popular languages.
If you're trying to manage a web site, configure servers, and write CGI scripts, this is the book for you. Written by the author of Perl's CGI.pm module, this book really does cover everything.
This small, delightful book is just the book for the experienced programmer wanting to learn Perl. It is not only free of technical errors, it is truly a pleasure to read. It is about Perl as a serious programming language.
This book includes thorough coverage of Perl's object model, and how to develop modules and contribute them to CPAN. It covers the debugger particularly well.
In addition to the Perl-related publications listed here, the following books came in handy when writing this book. They were used for reference, consultation, and inspiration.
The Art of Computer Programming, by Donald Knuth, Volumes I-III: "Fundamental Algorithms," "Seminumerical Algorithms," and "Sorting and Searching"; Addison-Wesley (3rd Edition, 1997).
Introduction to Algorithms, by Thomas H. Cormen, Charles E. Leiserson, and Ronald L. Rivest; MIT Press and McGraw-Hill (1990).
Algorithms in C, by Robert Sedgewick; Addison-Wesley (1992).
The Art of Mathematics, by Jerry P. King; Plenum (1992).
The Elements of Programming Style, by Brian W. Kernighan and P.J. Plauger; McGraw-Hill (1988).
The UNIX Programming Environment, by Brian W. Kernighan and Rob Pike; Prentice-Hall (1984).
POSIX Programmer's Guide, by Donald Lewine; O'Reilly & Associates (1991).
Advanced Programming in the UNIX Environment, by W. Richard Stevens; Addison-Wesley (1992).
TCP/IP Illustrated, by W. Richard Stevens, et al., Volumes I-III; Addison-Wesley (1992-1996).
Web Client Programming with Perl, by Clinton Wong; O'Reilly & Associates (1997).
HTML: The Definitive Guide, by Chuck Musciano and Bill Kennedy; O'Reilly & Associates (3rd Edition, 1998).
The New Fowler's Modern English Usage, edited by R.W. Burchfield; Oxford (3rd Edition, 1996).
Official Guide to Programming with CGI.pm, by Lincoln Stein; John Wiley & Sons (1997).