@book { AnalytischesCustomerRelationshipManagement,
    title = "Analytisches Customer Relationship Management",
    author = "Balint {Tolnay-Knefely}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832482244",
    url = "https://m.diplom.de/document/223440"
}