@book { PreisdifferenzierungimFlugpassagiergeschft,
    title = "Preisdifferenzierung im Flugpassagiergeschäft",
    author = "Verena {Blaeser}",
    year = "1999",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832413736",
    url = "https://m.diplom.de/document/217053"
}