@book { DasUrchristentum,
    title = "Das Urchristentum",
    subtitle = "Eine kritische Bilanz seiner Erforschung",
    author = "Gerd {Lüdemann}",
    year = "2002",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1093761"
}