@book { MobilesMarketingWelcheErkenntnisseliefertdieForschung,
    title = "Mobiles Marketing - Welche Erkenntnisse liefert die Forschung?",
    author = "Sonja {Hammel}",
    year = "2015",
    publisher = "BACHELOR + MASTER PUBLISHING",
    address = "Hamburg, Deutschland",
    url = "https://m.bachelor-master-publishing.de/document/296779"
}