@book { ZuNiklasLuhmannSozialeSysteme,
    title = "Zu: Niklas Luhmann - Soziale Systeme",
    author = "Christoph {Tautz}",
    year = "2005",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638339841",
    url = "https://www.hausarbeiten.de/document/33535"
}