Cita APA (7th ed.)

Luhmann, N. (1990). Essays on self-reference. Columbia University Press.

Cita Chicago (17th ed.)

Luhmann, Niklas. Essays on Self-reference. New York: Columbia University Press, 1990.

Cita MLA (9th ed.)

Luhmann, Niklas. Essays on Self-reference. Columbia University Press, 1990.