@book { BulgarienInternationaleBeziehungeninGeschichteKulturundKunstBulgarischeSammlungBd4,
    title = "Bulgarien. Internationale Beziehungen in Geschichte, Kultur und Kunst (= Bulgarische Sammlung, Bd. 4)",
    author = "Wolfgang {Gesemann} and Kyrill {Haralampieff} and Helmut {Schaller}",
    year = "1984",
    publisher = "Biblion",
    address = ", Germany",
    doi = "10.3726/b12580",
    url = "https://www.peterlang.com/document/1067030"
}