@book { ViralMarketingAnstzeundImplementierung,
    title = "Viral Marketing - Ansätze und Implementierung",
    author = "Ulrike {Neumann}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836623230",
    url = "https://m.diplom.de/document/226200"
}