@book { BulgarienJahrbuch2012, title = "Bulgarien-Jahrbuch 2012", author = "Sigrun {Comati} and Helmut {Schaller} and Wolfgang {Gesemann} and Raiko {Krauß}", year = "2014", publisher = "Biblion", address = ", Germany", doi = "10.3726/b12817", url = "https://www.peterlang.com/document/1067540" }