@book { KrisenmanagementimMittelstand,
    title = "Krisenmanagement im Mittelstand",
    author = "Michael {Döllner}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832472856",
    url = "https://m.diplom.de/document/222583"
}