I have published this image as author under the Creative-Commons-Licence CC BY-SA 4.0.. This means that free online usage outside of Wikimedia projects under the following terms of licence is possible:
The copyright is hold by the artist. This work is licensed under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation (http://www.gnu.org/copyleft/fdl.html)