@book { DieKonzeptiondesKundenrckgewinnungsmanagements,
    title = "Die Konzeption des Kundenrückgewinnungsmanagements",
    author = "Martina {Makosch}",
    year = "2010",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783842806146",
    url = "https://m.diplom.de/document/228100"
}