@book { KrisenmanagementintouristischenEinheiten,
    title = "Krisenmanagement in touristischen Einheiten",
    author = "Gerald {Kröll}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836602617",
    url = "https://m.diplom.de/document/228313"
}