@book { InstrumentezurKundenbindungfrReiseveranstalter,
    title = "Instrumente zur Kundenbindung für Reiseveranstalter",
    author = "Dirk {Fabritz}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832409500",
    url = "https://m.diplom.de/document/216848"
}