@book { InvestmentsparendieSpareinlage2009,
    title = "Investmentsparen - die Spareinlage 2009?",
    author = "Dietmar {Sollmann}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832403652",
    url = "https://m.diplom.de/document/216346"
}