{{cite web | url=http://www.europeana.eu/resolve/record/08604/A2841B4924BEF9931C62E29AC9B23C4441C51691|title=Wolken|accessdate=2013-05-21 |publisher=Europeana}}

<ref>{{cite web | url=http://www.europeana.eu/resolve/record/08604/A2841B4924BEF9931C62E29AC9B23C4441C51691|title=Wolken|accessdate=2013-05-21 |publisher=Europeana}}</ref>