The icons are mostly derived work from other icons. As such they are
licensed accordingly to the original license:

Project                 License                   File
----------------------------------------------------------------------------
Nuvola                  LGPL                      image_LICENSE_Nuvola.txt

Unless stated in this file, icons are the work of Enthought, and are
released under a 3 clause BSD license.

Files and orginal authors:
----------------------------------------------------------------------------
examples/tutorials/images:
                                 next.png | Nuvola
                         parent.png | Nuvola
                       previous.png | Nuvola
                         reload.png | Nuvola
                            run.png | Nuvola