@book { ProjektcontrollingundITLeistungsverrechnung,
    title = "Projektcontrolling und IT-Leistungsverrechnung",
    author = "Daniel {Humberg}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832460136",
    url = "https://m.diplom.de/document/221251"
}