All rendered images, screen shots, photos, blend files and articles are licensed under CC-BY-SA 3.0 or later, if no explicit license is mentioned in the corresponding article.

This means:

You are free to Share (to copy, distribute and transmit the work). You are free to remix (to adapt the work). You are free to make commercial use of the work. Under the following conditions:

Attribution — You must attribute the work in the manner specified by the author or licensor (but not in any way that suggests that they endorse you or your use of the work).
Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.

For attribution please use Thomas Weller, WelliSolutions