[1] Borůvka O.: Lineare Differentialtransformationen 2. Ordnung. VEB Berlin 1967. English translation: Linear Differential Transformations of the Second Order. The English Univ. Press, London, 1971. MR 0463539

[2] Neuman F.: A Role of Abel's Equation in the Stability Theory of Differential equations. Aequationes Mathematicae, 6 (1971) pp. 66-70. MR 0299899 | Zbl 0215.43803

[3] Neuman F.: $L^2$ - Solution of $y''=q(t) y$ and a Functional Equation. Aequationes Mathematicae. 6, 1971, pp. 162-169. MR 0291562 | Zbl 0225.34022

[4J Neuman F.: Relation between the Distribution of the Zeros of the Solutions of the 2nd Order linear differential Equation and the Boundedness of these Solutions. Acta Mathematica Academiae Scientiarum Hungaricae. Tomus 19 (1-2), (1968), pp. 1-6. MR 0228750

[5] Ryshik I. M., Grandstein I. S.: Tables of Series, Products and Integrals. VEB Berlin 1957.