@book { Seniorenmarketing,
    title = "Seniorenmarketing",
    subtitle = "Theoretische Grundlagen - Empirische Untersuchung",
    author = "Franziska {Rutishauser}",
    year = "2005",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832485610",
    url = "https://m.diplom.de/document/223760"
}