[1] Dirac, P.A.M. (1958) The Principles of Quantum Mechanics. 4th Edition, Oxford Univ. Press, Oxford, 89-94; 121-125; 130-136; 136-139; 207-211; 227-237; 248-252.
[2] Debye, P. (1972) Annalen der Physik, 39, 789-839.
[3] Ginzburg, V.L. and Landau, L.D. (1950) Zh. Eksp. Teor. Fiz., 20, 1064-1082. [English translation in: L. D. Landau, “Collected papers,” Oxford: Pergamon Press (1965), 546.]