@book { KostenfalleMesse,
    title = "Kostenfalle Messe?",
    author = "Anja {Steinrücken}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832486013",
    url = "https://m.diplom.de/document/223795"
}