@book { WordofMouthInfluencesonthechoiceofRecommendationSources,
    title = "Word-of-Mouth: Influences on the choice of Recommendation Sources",
    author = "Klaus {Schöfer}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832441456",
    url = "https://m.diplom.de/document/219769"
}