@book { MarkenkommunikationmitTestimonials,
    title = "Markenkommunikation mit Testimonials",
    author = "Marc {Fischer}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832463991",
    url = "https://m.diplom.de/document/221827"
}