@book { DieTheorieselbstreferentiellerSystemebeiNiklasLuhmann,
    title = "Die Theorie selbstreferentieller Systeme bei Niklas Luhmann",
    author = "Susanne {Dera}",
    year = "2006",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638480130",
    url = "https://www.hausarbeiten.de/document/52253"
}