@book { TourismusinderEU,
    title = "Tourismus in der EU",
    author = "Xenia {Kempter}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832478018",
    url = "https://m.diplom.de/document/223067"
}