@book { DasMarketing,
    title = "Das Marketing",
    subtitle = "Modell für eine erfolgreiche Wahlkampagne",
    author = "Harald {Kohlberger}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832451271",
    url = "https://m.diplom.de/document/220654"
}