@book { Hamburghartzart,
    title = "Hamburg hart + zart",
    author = "Christoph {Ernst} and Dagmar {Hecht} and Michael {Jalowczarz} and Jürgen {Müller} and Vera {Rosenbusch} and Irina {Tegen} and Petra {Wilson} and Olaf {Wulf} and Hilkka {Zebothsen} and Autorengruppe {Blut und Feder}",
    year = "2016",
    publisher = "Bedey Media GmbH",
    address = "Hamburg, Deutschland",
    url = "https://kaderaverlag.openpublishing.com/document/317932"
}