@book { REITSinDeutschland,
    title = "REITS in Deutschland",
    author = "Michael {Maas}",
    year = "2007",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783836604765",
    url = "https://m.diplom.de/document/228970"
}