@book { DerPlandesJosefPopperLynkeus,
    title = "Der Plan des Josef Popper-Lynkeus",
    subtitle = "Vorwort von Richard Coudenhove-Kalergi",
    author = "Frederick P. {Hellin} and Robert {Plank}",
    year = "1978",
    publisher = "Peter Lang Verlag",
    address = "Lausanne, Switzerland",
    url = "https://www.peterlang.com/document/1070661"
}