Photo: This illustration was made by Peter Potrowl. Please credit this with : © Peter Potrowl in the immediate vicinity of the image. A link to my website sitemai.eu would be much appreciated but isn't mandatory. An email to Peter Potrowl would be appreciated too. Do not copy this image illegally by ignoring the terms of the license below, as it is not in the public domain. If you would like special permission to use, license, or purchase the image please contact me Peter Potrowl to negotiate terms. More free pictures in my website. Donations are accepted here and here. (CC BY-SA 3.0)