@book { concordiamagna,
    title = "«concordia magna»",
    subtitle = "Der Magdeburger Stadtfrieden vom 21. Januar 1497",
    author = "Gudrun {Wittek}",
    year = "2006",
    publisher = "Peter Lang Verlag",
    address = "Berlin, Germany",
    url = "https://www.peterlang.com/document/1099968"
}