@book { Der11September2001,
    title = "Der 11. September 2001",
    subtitle = "Fragen, Folgen, Hintergründe",
    author = "Sabine {Sielke}",
    year = "2002",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1094142"
}