@book { DiebuerlicheOstsiedlungdesMittelaltersinNordostdeutschland,
    title = "Die bäuerliche Ostsiedlung des Mittelalters in Nordostdeutschland",
    author = "Felix {Biermann} and Günter {Mangelsdorf}",
    year = "2021",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1099823"
}