@book { ProblemederPersonalplanung,
    title = "Probleme der Personalplanung",
    author = "Ilka {Ruland}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Germany",
    doi = "10.3239/9783832437046",
    url = "https://m.diplom.de/document/219389"
}