@book { SchattenwirtschaftinDeutschland,
    title = "Schattenwirtschaft in Deutschland",
    author = "Marcel {Sarman}",
    year = "2004",
    publisher = "Diplom.de",
    address = "Hamburg, Deutschland",
    doi = "10.3239/9783832476281",
    url = "https://m.diplom.de/document/222903"
}