@book { VariettenderdeutschenSprache,
    title = "Varietäten der deutschen Sprache",
    author = "Jörg {Hennig} and Jürgen {Meier}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1083502"
}