@book { WieeffektivistSocialMediaMarketingwirklich,
    title = "Wie effektiv ist Social Media Marketing wirklich?",
    author = "Matthias {Thimm}",
    year = "2019",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    url = "https://www.hausarbeiten.de/document/498685"
}