1. Weaver, W., Shannon, C. E.: The Mathematical Theory of Communication ( Univ. of Illinois Press, Urbana 1949 )
2. Brillouin, L.: Science and Information Theory ( Academic, New York 1956 )
3. Ashby, W. R.: An Introduction to Cybernetics ( Chapman and Hall, London 1956 )
4. Bongard, N. M.: “On the Notion of Useful Information” in Problems of Cybernetics ( Fizmatgiz, Moscow 1963 ) 9, pp. 71–102 (in Russian)
5. Stratonovitch, R. L.: Information Theory ( Sovetskoye Radio, Moscow 1975 ) (in Russian)