brain; the origin of adaptive behavior, 2nd ed. (Electronic versions on Internet Archive). Beer, S. 1974, Designing Freedom, CBC Learning Systems, Toronto, 1974; and John Wiley, London and New York, 1975. Translated into Spanish and Japanese. Beer, S. 1975, Platform for Change, John Wiley, London and New York. Reprinted with corrections 1978. Beer, S. 1979, The Heart of Enterprise, John Wiley, London and New York. Reprinted with corrections 1988. Beer, S. 1981, Brain of the Firm; Second Edition (much extended), John Wiley, London and New York. Reprinted 1986, 1988. Translated into Russian. Beer, S. 1985, Diagnosing the System for Organisations; John Wiley, London and New York. Translated into Italian and Japanese. Reprinted 1988, 1990, 1991. Conant, R. 1981, Mechanisms of Intelligence: Ross Ashby's papers and writings, Intersystems Publications, . External links The Law of Requisite Variety in the Principia Cybernetica Web, 2001. Systems concepts and 9/11 Allenna Leonard on Requisite Variety All references to The Law of Requisite Variety in Ross Ashby's journal 1953–1961. Management Cybernetics: The Law of Requisite Variety Livas short introductory videos on YouTube Practopoiesis: How biological systems get their variety The 1973 CBC Massey Lectures, "Designing Freedom" Cybernetics