Programming Perl, by Wall, Christiansen and Orwant, O'Reilly.
Perl Debugger Pocket Reference, by Richard Foley, O'Reilly.
Perl Debugged, by Peter Scott and Ed Wright, Addison-Wesley.
Perl Medic, by Peter Scott, Addison-Wesley.
perldebug man page
perldiag man page
“brian d foy's guide to debugging”: www.panix.com/~comdog/solve_any_perl_problem.pod
