Official documentation: docs.python.org.
General History and overview: Python (programming language).
Quick reference sheet. Highly recommended. Python 2.7 Quick Reference By Richard Gruet. @ rgruet.free.fr…
Google Python Style Guide By Amit Patel, Antoine Picard, Eugene Jhong, Jeremy Hylton, Matt Smart, Mike Shields. @ google-styleguide.googlecode.com…
Official documentation: perldoc.perl.org.
General history and overview: Perl.
See also: Perl Books Survey 2002.