A Mathematical Theory of Communication, published in 1948 by mathematician and computer scientist Claude Shannon, was one of the founding works of the field of information theory. It developed the concepts of information entropy and redundancy.
Reference
C. E. Shannon, A mathematical theory of communication, Bell System Technical Journal, vol. 27, pp. 379-423 and 623-656, (July and October, 1948)
External Link
http://cm.bell-labs.com/cm/ms/what/shannonday/paper.html