- A first Course In Partial Differential Equations H F Weinberger Dover Publications

-The dynamical Theory of Sound" by Horace Lamb 1960

-G.N.Watson A treatise on the Theory of Bessel Functions,2nd ed. Cambridge Edition, England:

Cambridge University Press,1966.

-F.Bowman Introduction to Bessel Functions Dover Pub New York 1958.

-Titchmarsh E.C. Eigenfunction expansions I (2ed., Oxford, 1962)

- Szego - Orthogonal Polynomials

- An Introduction to Operators on the Hardy-Hilbert Space - Springer 2007

-Akhiezer N.I., Glazman I.M. Theory of linear operators in Hilbert space (2ed., Dover, 1993)

-Andrews G.E., Askey R., Roy R. Special functions (CUP 1999)

-Special.Functions.of.Mathematical.Physics_Nikiforov.and.Uvarov (english)

- Timoshenko - Theory of plates and shells

-Lord Rayleigh The Theory of Sound Vol.1 Vol II (1945) Dover Pub New York

-A.F. Nikiforov - V.B. Uvarov: Special Functions of Mathematical Physics, Birkhauser, Basel, 1988.

-P.M. Morse. K,Unoingard, Theoretical Acoustics, Princeton University Press, Princeton, 1986.

-P.M. Morse, K. Unoingard Vibration and Sound, second ed, McGra-Hill, New York, 1948.

-A.Yariv Optical Electronics Saunders College Publishing 1991.

-S.Ramo, J.R. Whinnery, T. Van Duzer Fields and waves in communication electronics second ed. Wiley &Sons 1965.