Source notes for berlin environmental zone

The provider of the data is Geoportal Berlin / Umweltzone - Berlin.
The data is licensed under Data licence Germany – attribution – Version 2.0;
The license text is available at www.govdata.de/dl-de/by-2-0. The data is located under
https://hub.arcgis.com/datasets/esri-de-content::umweltzone-berlin/about.