(en) Heinz von Foerster, Margaret Mead e Hans Lukas Teuber: Cybernetics, Circular Causal and Feedback Mechanisms in Biological and Social Systems S/T Transactions of the Ninth Conference, March 20-21, 1952, Nòva York, N.Y. ed:Josiah Macy, Jr. Foundation in actes de la 9a « conferéncia Macy »|année = 1953|pages totales = 184|oclc = 2403472}}.