@book { DerEinkaufimEBusinessZeitalter,
    title = "Der Einkauf im E-Business-Zeitalter",
    author = "Thomas {Frahling}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832461195",
    url = "https://m.diplom.de/document/221580"
}