Learning Perl, 2nd Edition. O'Reilly & Associates, 1997.
Schwartz, Randal L. & Tom Christiansen.
Is there anyone who learned Perl without this book? This is the standard Perl beginner's manual. That said, it's pretty dense, so if you'd like an easier book to start with, we'd recommend Teach Yourself Perl in 21 Days, described below. Learning Perl is an O'Reilly book, so you know it's going to be good!

Teach Yourself Perl 5 in 21 Days, 2nd Edition. Sams, 1996.
Till, David
This is a great book if you'd like to learn Perl. It's got a lot of information, & it presents it in an efficient manner, with plenty of examples. I'm not sure you'll learn Perl in 21 days, but it will help you get started!