@book { Hflichkeitsstile,
    title = "Höflichkeitsstile",
    subtitle = "2., korrigierte Auflage",
    author = "Heinz-Helmut {Lüger}",
    year = "2002",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1093117"
}