@book { GuteLaunekenntkeinAlter,
    title = "Gute Laune kennt kein Alter",
    author = "Martina {Rühl}",
    year = "2017",
    publisher = "Schlütersche Verlagsgesellschaft mbH & Co. KG",
    address = ", Deutschland",
    url = "https://schluetersche.openpublishing.com/document/404109"
}