@book { GrundzgedesBrgerlichenRechts,
    title = "Grundzüge des Bürgerlichen Rechts",
    author = "Peter {Bähr}",
    year = "2013",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1220888"
}