@book { SchlossMalberginderKyllburgerWaldeifel,
    title = "Schloss Malberg in der Kyllburger Waldeifel",
    author = "Ralph {Foss}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836602679",
    url = "https://m.diplom.de/document/228315"
}