@book { DieFinanzplanung,
    title = "Die Finanzplanung",
    author = "Matthias {Richling}",
    year = "2001",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832437817",
    url = "https://m.diplom.de/document/219462"
}