@book { OperationalDueDiligence,
    title = "Operational Due Diligence",
    author = "Patrick {Ott}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836638463",
    url = "https://m.diplom.de/document/227382"
}