@book { Differenzen,
    title = "Differenzen?",
    author = "E.W.B. {Hess-Lüttich} and Ulrich {Müller} and Siegrid {Schmidt} and Klaus {Zelewitz}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1106625"
}