@book { ElectronicWordofMouth,
    title = "Electronic Word of Mouth",
    author = "Stefania {Lettini}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832453787",
    url = "https://m.diplom.de/document/220940"
}