@book { DasGeheimnisderGrfin,
    title = "Das Geheimnis der Gräfin",
    author = "Bettina {Szrama}",
    year = "2020",
    publisher = "dp DIGITAL PUBLISHERS GmbH",
    address = "Stuttgart, Deutschland",
    url = "https://shop.digitalpublishers.de/document/593731"
}