@book { DerSeniorenmarktZielgruppefrdenHandel,
    title = "Der Seniorenmarkt - Zielgruppe für den Handel",
    author = "Katja {Reinhold}",
    year = "2008",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638026499",
    url = "https://www.hausarbeiten.de/document/89302"
}