@book { DiscountBroking,
    title = "Discount Broking",
    author = "Jörg {Siegmund}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832430214",
    url = "https://m.diplom.de/document/218739"
}