@book { CallCenterimFocusdesmodernenCustomerRelationshipManagements,
    title = "Call Center im Focus des modernen Customer Relationship Managements",
    author = "Klaus-Volker {Schulte zu Sodingen}",
    year = "2000",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832424411",
    url = "https://m.diplom.de/document/218239"
}