A.M. Kuchling (3 de julio de 2010). «What’s New in Python 2.7». Consultado el 7 de octubre de 2012. «Much as Python 2.6 incorporated features from Python 3.0, version 2.7 incorporates some of the new features in Python 3.1. The 2.x series continues to provide tools for migrating to the 3.x series.»