@book { FluchtwegBulgarien,
    title = "Fluchtweg Bulgarien",
    subtitle = "Die verlängerte Mauer an den Grenzen zur Türkei, Jugoslawien und Griechenland",
    author = "Stefan {Appelius}",
    year = "2019",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    doi = "10.3726/b15612",
    url = "https://www.peterlang.com/document/1110791"
}