@book { DerEuro,
    title = "Der Euro",
    subtitle = "Geburt, Erfolg, Zukunft",
    author = "Otmar {Issing}",
    year = "2012",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1219054"
}