1. A.S. Davydov, Quantum Mechanics, 2nd edn. (Pergamon Press, Oxford, 1976)
2. L.D. Landau, E.M. Lifshitz, Field Theory (Pergamon Press, Oxford, 1958)
3. H. Goldstein, Classical Mechanics (Addison-Wesley Publishing Company, Inc., Third Printing, 1953)
4. W. Heitler, The Quantum Theory of Radiation (Clarendon Press, Oxford, 1954)
5. I.N. Broushtein, K.A. Semendyayev, Handbook of Mathematics (Van Nostrand Reinhold Company, New York, 1985)