@book { ImmaterielleundmaterielleMotivationsinstrumente,
    title = "Immaterielle und materielle Motivationsinstrumente",
    author = "Torsten {Witte}",
    year = "1997",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832402242",
    url = "https://m.diplom.de/document/216170"
}