@book { DasSteuersysteminRuland,
    title = "Das Steuersystem in Rußland",
    author = "Ellen {Gaus}",
    year = "1998",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832407063",
    url = "https://m.diplom.de/document/216633"
}