@book { InformationsgehaltvonRatingnderungen,
    title = "Informationsgehalt von Ratingänderungen",
    author = "Stefan {Heil}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832438845",
    url = "https://m.diplom.de/document/219528"
}