Current Perl documentation can be found at perldoc.perl.org.
Here is our local, out-dated (pre-5.6) version:
Tk is a completely Perl-based, object-oriented interface to the Tk toolkit that doesn't force you to use Tcl just to get at Tk. Sx is an interface to the Athena Widget set. Both are available from CPAN. See the directory http://www.perl.com/CPAN/modules/by-category/08_User_Interfaces/
Invaluable for Perl/Tk programming are: the Perl/Tk FAQ at http://w4.lns.cornell.edu/~pvhp/ptk/ptkTOC.html , the Perl/Tk Reference Guide available at http://www.perl.com/CPAN-local/authors/Stephen_O_Lidie/ , and the online manpages at http://www-users.cs.umn.edu/~amundson/perl/perltk/toc.html .