@book { DasGeneralgouvernementNiederrhein,
    title = "Das Generalgouvernement Niederrhein",
    author = "Peter {Opitz-von Bardeleben}",
    year = "2013",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/978-3-653-02320-6",
    url = "https://www.peterlang.com/document/1047436"
}