@book { WordofMouthimMarketingundindenSozialwissenschaften,
    title = "Word of Mouth im Marketing und in den Sozialwissenschaften",
    author = "Stephan {Schmidt}",
    year = "2008",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836615136",
    url = "https://m.diplom.de/document/225898"
}