@book { ProduktpolitikinderTelekommunikation,
    title = "Produktpolitik in der Telekommunikation",
    author = "Matthias {König}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832434618",
    url = "https://m.diplom.de/document/219128"
}