Qvortrup, Lars. “Niklas Luhmann: Sociale Systemer. Grundrids Til En Almen Teori”. MedieKultur: Journal of media and communication research 10, no. 22 (September 2, 1994): 2 pages. Accessed November 22, 2024. https://tidsskrift.dk/mediekultur/article/view/1017.