@book { BewertungvonAktienoptionen,
    title = "Bewertung von Aktienoptionen",
    author = "Michael {Stahl}",
    year = "2006",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832494346",
    url = "https://m.diplom.de/document/224567"
}