@book { SilvaeBulgaricaeVortrgevom6November2009anlsslichdes80GeburtstagesvonDrHorstRhling,
    title = "Silvae Bulgaricae. Vorträge vom 6. November 2009 anlässlich des 80. Geburtstages von Dr. Horst Röhling",
    author = "Helmut {Schaller} and Rumjana {Zlatanova}",
    year = "2012",
    publisher = "Biblion",
    address = ", Germany",
    doi = "10.3726/b12318",
    url = "https://www.peterlang.com/document/1067453"
}