@book { CRMSystemeinderffentlichenVerwaltung,
    title = "CRM-Systeme in der öffentlichen Verwaltung",
    author = "Marc {Petry}",
    year = "2002",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832459932",
    url = "https://m.diplom.de/document/221440"
}