Foundations of Computer Science
Aho, Alfred and Ullman, Jeffrey, Computer Science Press, W.H. Freeman and Company New York, 1992.
Learning Perl, Second Edition
Randal L. Schwartz and Tom Christiansen, O'Reilly & Associates, Inc., Sebastpool, CA (1997).
The exercises and some example scripts from this book are available through FTP.
Programming Perl, Second Edition
Larry Wall, Tom Christiansen and Randal L. Schwartz, O'Reilly & Associates, Inc., Sebastpool, CA (1996).
Official Guide to Programming with CGI.pm
Lincoln Stein, John Wiley & Sons, Inc. (1998).