@book { ProcurementDecisionsintheAirlineIndustry,
    title = "Procurement Decisions in the Airline Industry",
    author = "Tobias {Rudeloff}",
    year = "2009",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836637763",
    url = "https://m.diplom.de/document/227313"
}