1. V. S. Vladimirov, Equations of Mathematical Physics (Marcel Dekker, New York, 1971).
2. B. M. Levitan, “Expansion in Fourier series and integrals with Bessel functions,” Usp. Mat. Nauk 6(2), 102–143 (1951).
3. S. M. Nikol’skii, Approximation of Functions of Several Variables and Imbedding Theorems (Springer-Verlag, New York, 1975).
4. B. M. Levitan and I. S. Sargsjan, Introduction to Spectral Theory: Self-Adjoint Ordinary Differential Operators (Am. Math. Soc., Providence, R.I., 1975).
5. V. A. Abilov and F. V. Abilova, “Approximation of functions by Fourier-Bessel sums,” Russ. Math. (Izv. Vyssh. Uchebn. Zaved. Mat.) 45(8), 1–7 (2001).