cpython/Doc/tools/templates/indexsidebar.html

<h3>{% trans %}Download{% endtrans %}</h3>
<p><a href="{{ pathto('download') }}">{% trans %}Download these documents{% endtrans %}</a></p>
<h3>{% trans %}Docs for other versions{% endtrans %}</h3>
<ul>
  <li><a href="https://docs.python.org/2.7/">{% trans %}Python 2.7 (stable){% endtrans %}</a></li>
  <li><a href="https://docs.python.org/3.5/">{% trans %}Python 3.5 (stable){% endtrans %}</a></li>
  <li><a href="https://docs.python.org/3.7/">{% trans %}Python 3.7 (in development){% endtrans %}</a></li>
  <li><a href="https://www.python.org/doc/versions/">{% trans %}Old versions{% endtrans %}</a></li>
</ul>

<h3>{% trans %}Other resources{% endtrans %}</h3>
<ul>
  {# XXX: many of these should probably be merged in the main docs #}
  <li><a href="https://www.python.org/dev/peps/">{% trans %}PEP Index{% endtrans %}</a></li>
  <li><a href="https://wiki.python.org/moin/BeginnersGuide">{% trans %}Beginner's Guide{% endtrans %}</a></li>
  <li><a href="https://wiki.python.org/moin/PythonBooks">{% trans %}Book List{% endtrans %}</a></li>
  <li><a href="https://www.python.org/doc/av/">{% trans %}Audio/Visual Talks{% endtrans %}</a></li>
</ul>