@book { ImmobilienLeasing,
    title = "Immobilien-Leasing",
    author = "Sonja {Meyer}",
    year = "1999",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832418250",
    url = "https://m.diplom.de/document/217446"
}