@book { LoyaltyManagementintheAirlineIndustry,
    title = "Loyalty Management in the Airline Industry",
    author = "Ben {Beiske}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832454647",
    url = "https://m.diplom.de/document/220778"
}