@book { BusinessTravelManagementStrategies,
    title = "Business Travel Management Strategies",
    author = "Annette {Rocholl}",
    year = "2012",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783842842007",
    url = "https://m.diplom.de/document/229323"
}