@book { DiversifikationvonUnternehmungen,
    title = "Diversifikation von Unternehmungen",
    author = "Daniela {Schulz}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832407124",
    url = "https://m.diplom.de/document/216231"
}