@book { Aktienoptionsprogramme,
    title = "Aktienoptionsprogramme ",
    author = "Gunter {Fischer}",
    year = "2000",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832420123",
    url = "https://m.diplom.de/document/217447"
}