@book { 30JahreKrieg,
    title = "30 Jahre Krieg",
    author = "David {North} and Ute {Reissner}",
    year = "2020",
    publisher = "MEHRING Verlag",
    address = "Essen, Deutschland",
    url = "https://mehring.openpublishing.com/document/936303"
}