@book { SmtlicheWerkeBand4,
    title = "Sämtliche Werke - Band 4",
    author = "Ferdinand {van Ingen} and Hans-Gert {Roloff}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1078825"
}