@book { PolensStaatlichkeitinsiebenJahrhunderten, title = "Polens Staatlichkeit in sieben Jahrhunderten", author = "Adrianna {Michel}", year = "2015", publisher = "Peter Lang Verlag", address = "Berlin, Germany", doi = "10.3726/978-3-653-04696-0", url = "https://www.peterlang.com/document/1048727" }