@book { WeltgesellschaftbeiNiklasLuhmann,
    title = "Weltgesellschaft bei Niklas Luhmann",
    author = "Thomas {Schröder}",
    year = "2005",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638364300",
    url = "https://www.hausarbeiten.de/document/36930"
}