1. Kullback, S., Leibler, R.A.: On information and sufficiency. The Annals of Mathematical Statistics 22(1), 79–86 (1951)
2. Chentsov, N.N.: A nonsymmetric distance between probability distributions, entropy and the Pythagorean theorem. Mathematical Notes of the Academy of Sciences of the USSR 4(3), 323–332 (1968)
3. Chentsov, N.N.: Statistical Decision Rules and Optimal Inference. Nauka, Moscow, U.S.S.R (1972) (in Russian)
4. English translation: AMS, Providence (1982)
5. Umegaki, H.: Conditional expectation in an operator algebra. IV. entropy and information. Kodai Mathematical Seminar Reports 14(2), 59–85 (1962)