@book { Seniorenhandys,
    title = "Seniorenhandys",
    author = "Ines {Geringer}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836605212",
    url = "https://m.diplom.de/document/229004"
}