1. V. M. Agranovich, Teoriya èksitonov, Izd. Nauka, Moscow, 1968.
2. E. Cartan, Le principe de dualité et la théorie des groupes simples et semi-simples, Bull. Sci. Math. France 49 (1925), 367 - 374.
3. E. Cartan: The Theory of Spinors, Second Edition, Hermann, Paris, 1966, 120.
4. E. I. Dinaburg, On the relations among various entropy characteristics of dynamical systems, in Dynamical Systems, Ya. G. Sina i, ed., Advanced Series in Nonlinear Dynamics 1, Amer. Math. Soc, New York, 1972, 337 - 350.
5. E. Fermi, Thermodynamics, Second Edition, Dover Publ., New York, 1956, 46 - 76.