1. 1. B. M. Levitan, Generalized translation operators and some of their applications. Jerusalem: Israel Program for Scientific Translations, 1964.
2. 2. Y. Smirnov and A. V. Turbiner, Hidden sl 2-algebra of finite-difference equations 1, Modern Physics Letters, vol. A10, pp. 1795{1801, 1995.
3. 3. W. Miller, Lie theory and special functions. Academic Press, 1968.
4. 4. P. Appell and J. K. de Feriet, Fonctions Hypergeometriques et Hyperspheriques: Polynomes d'Hermite. Paris: Gauthier-Villars, 1926.
5. 5. H. W. Gould, A. Hopper, et al., Operational formulas connected with two generalizations of Hermite polynomials, Duke Mathematical Journal, vol. 29, no. 1, pp. 51{63, 1962.