<hi xmlns="http://www.tei-c.org/ns/1.0" rend="bold">Python Software Fundation</hi> (1990-2016): <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">difflib - Helpers for Computing Deltas </hi><ref xmlns="http://www.tei-c.org/ns/1.0" target="https://docs.python.org/2/library/difflib.html">https://docs.python.org/2/library/difflib.html</ref> [letzter Zugriff 15. Oktober 2015].