@book { IntelligenteStrategienfrTKDienstleister,
    title = "Intelligente Strategien für TK-Dienstleister",
    author = "Manuel {Hoffrichter}",
    year = "2003",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832470388",
    url = "https://m.diplom.de/document/222347"
}