@book { PrimrmarktforschungMethodenundHerausforderungen,
    title = "Primärmarktforschung. Methoden und Herausforderungen",
    author = "Annika {Fanzlau}",
    year = "2013",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783656428527",
    url = "https://www.hausarbeiten.de/document/214916"
}