@book { ControllinginKleinundKleinstunternehmen,
    title = "Controlling in Klein- und Kleinstunternehmen",
    author = "Bernd {Schwieters}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836627160",
    url = "https://m.diplom.de/document/226634"
}