All icons in the oxygen/ directory are taken from the Oxygen icon set for KDE4.
The Oxygen icons are dual-licensed under the Creative Common
Attribution-ShareAlike 3.0 License or the GNU Library General Public License.

The packet_view icon is also taken from Oxygen, and has been
modified to remove the - sign inside the magnifying glass.

The x-regina mimetype icon includes the generic "sheet of paper" from
the Oxygen icon set.

The csvexport icons are taken from the KDE3 slick icon set (view_text.png),
which was shipped with KDE3's kdeartwork module.
The slick icon set is (C) 2005 - Robert Cosgrove <rob@digital-confusion.net>.
