@book { MobileBrandingviaUMTS,
    title = "Mobile Branding via UMTS",
    author = "Thomas J. {Schäfer}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832489908",
    url = "https://m.diplom.de/document/224149"
}