@book { DerEinsatzmultimedialerInstrumenteinderMarktforschung,
    title = "Der Einsatz multimedialer Instrumente in der Marktforschung",
    author = "Frank {Beulke}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832411466",
    url = "https://m.diplom.de/document/217070"
}