Mathematical foundations of information theory - Khinchin, A. I︠A︡. (Aleksandr I︠A︡kovlevich), 1894-1959 (Dover Publications, 1957)
A translation of two papers " The entropy concept in probability theory [and] On the fundamental theorems of information theory", which appeared originally in Russian in Uspekhi Matematicheskikh Nauk., vol. VII, no. 3, 1953, pp.3-20 and vol. XI, no. 1, 1956, pp, 17-75.