@book { DieTouristikbrancheimInternet,
    title = "Die Touristikbranche im Internet",
    subtitle = "Eine Betrachtung aus Anbieter- und Nachfragersicht",
    author = "David {Vasicek}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832405076",
    url = "https://m.diplom.de/document/216224"
}