@book { DerFallvonAkkon,
    title = "Der Fall von Akkon",
    subtitle = "Untersuchungen zum Abklingen des Kreuzzugsgedankens am Ende des 13. Jahrhunderts",
    author = "Erwin {Stickel}",
    year = "1975",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1069767"
}