@book { DieGeneration50plus,
    title = "Die Generation 50plus",
    author = "Stefan {Trattner}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832478988",
    url = "https://m.diplom.de/document/223149"
}