@book { InvestitionundFinanzierung,
    title = "Investition und Finanzierung",
    author = "Hans {Putnoki} and Heike {Schwadorf} and Friedrich {Then Bergh}",
    year = "2011",
    publisher = "Vahlen",
    address = "München, Deutschland",
    url = "https://vahlen.openpublishing.com/document/1220774"
}