@book { CustomerLifetimeValueWasisteinKundewert,
    title = "Customer Lifetime Value. Was ist ein Kunde wert?",
    author = "Manuela {Strasser}",
    year = "2007",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638894272",
    url = "https://www.hausarbeiten.de/document/85418"
}