@book { ZumGebrauchdesKonjunktivsinBriefen,
    title = "Zum Gebrauch des Konjunktivs in Briefen",
    author = "Hanspeter {Züst}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1070565"
}