@book { SmtlicheWerkeBriefeDokumente,
    title = "Sämtliche Werke - Briefe - Dokumente",
    author = "P. M. {Mitchell}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1079090"
}