@book { DasNetworkMarketingKonzept,
    title = "Das Network-Marketing-Konzept",
    author = "Barbara {Seeger}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836601054",
    url = "https://m.diplom.de/document/228759"
}