@book { StrategicuseofCRM,
    title = "Strategic use of CRM",
    author = "Vladimir {Tosovic}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832445423",
    url = "https://m.diplom.de/document/220140"
}