@book { DasGeheimnisderverschollenenEngel,
    title = "Das Geheimnis der verschollenen Engel",
    author = "Peter {Jäger}",
    year = "2016",
    publisher = "Bedey Media GmbH",
    address = "Hamburg, Deutschland",
    url = "https://kaderaverlag.openpublishing.com/document/318331"
}