1. Mac Robert T. M.,Functions of a complex variable, 5th edit. 1962.
2. Erdelyi A., Magnus W., Oberhetinger F. and Tricomi E.,Higher transcendental functions, Vol. 1, Mc Graw Hill, 1953.
3. Titchmarch E. C.,Introduction to the theory of Fourier Integrals, Oxford, 1937.
4. Mac Robert T. M.,Multiplication formulae for the E-functions regarded as functions of their parameters, Pacific Journal of Math., Vol. 9 (1959).
5. Hardy G. H., Messen. of Math., 56, 1927.