@book { SpielzweierHerzen,
    title = "Spiel zweier Herzen",
    author = "Anne {Gracie} and Ute-Christine {Geiler}",
    year = "2020",
    publisher = "dp DIGITAL PUBLISHERS GmbH",
    address = "Stuttgart, Deutschland",
    url = "https://shop.digitalpublishers.de/document/917214"
}